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Preterm premature rupture of membranes >32 weeks’ estation: impact of revised practice guidelines

Arij Faksh, DO; Joseph R. Wax, MD; F. Lee Lucas, PhD; Angelina Cartin; Michael G. Pinette, MD

OBJECTIVE: The purpose of this study was to determine the perinatal impact of the 2007 American College of Obstetricians and Gynecolo- gists Practice Bulletin on preterm premature membrane rupture.

STUDY DESIGN: Perinatal outcomes were compared in women who had experienced preterm membrane rupture in the 3 years before the 2007 Practice Bulletin to similar women who experienced preterm pre- mature rupture of membranes in the 3 years after the issue and imple- mentation of the guideline.

RESULTS: After adjustment for gestational age at membrane rupture

and steroids, composite severe morbidity (death, respiratory distress

Obstet Gynecol 2011;205:340.e1-5.

p remained uncertain, p

doi: 10.1016/j.ajog.2011.05.036

340.e1 American Journal of Obstetrics & Gynecology OCTOBER 2011

syndrome, assisted ventilation for �6 hours, sepsis, pneumonia, grade 3 or 4 intraventricular hemorrhage, or necrotizing enterocolitis) was similar by group. Infants in the “after” group experienced less pneumo- nia and sepsis, similar respiratory morbidity, but more labor inductions and postpartum hemorrhage.

CONCLUSION: The new guideline significantly decreases severe neo- natal infections but is associated with more frequent labor induction and postpartum hemorrhage.

Key words: neonatal morbidity, prematurity, preterm premature

rupture of membranes

Cite this article as: Faksh A, Wax JR, Lucas FL, et al. Preterm premature rupture of membranes �32 weeks’ gestation: impact of revised practice guidelines. Am J

m c p o t

Preterm premature rupture of mem-branes (PPROM) affects 1-2% of pregnancies but is associated with up to 30-40% of preterm births.1 In the ab- sence of labor or complications that war- rant delivery, expectant care is often practiced until a gestational age is reached beyond which further observa- tion does not significantly reduce pre- maturity complications but potentially exposes the fetus to infection and in- flammation with associated long-term

From the Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology (Drs Faksh, Wax, and Pinette and Ms Cartin), and the Maine Center for Outcome Research and Evaluation (Dr Lucas), Maine Medical Center, Portland, ME.

Received Feb. 9, 2011; revised April 5, 2011; accepted May 18, 2011.

J.R.W. reports having served periodically as a consultant to the Gerson Lehrman Group over the past 3 years. The other 4 authors report no conflicts of interest.

Presented orally at the District I Meeting, American College of Obstetricians and Gynecologists, Bar Harbor, ME, Oct. 8-10, 2010.

Reprints not available from the authors.

negative consequences. Contemporary PPROM management incorporates glu- cocorticoids, broad-spectrum antibiot- ics, and fetal lung maturity assessment. Perinatal outcomes that are associated with this care suggest that expectancy may be abandoned at earlier gestational ages than previously considered.2-5

In April 2007, the American College of Obstetricians and Gynecologists (ACOG) published a revised Practice Bulletin that supported more active PPROM manage- ment at earlier gestational ages.6 However, 2 of 3 recommendations regarding deliv- ery timing were based on limited and in- consistent scientific evidence (level B) and included delivery at 32-33 weeks’ gestation with documented fetal lung maturity or when PPROM occurred at �34 weeks’ gestation. An additional recommendation to consider a single course of corticoste- roids at 32-33 weeks’ gestation, particu- larly if pulmonary immaturity was docu- mented, was based primarily on consensus and expert opinion (level C). Moreover, many supporting studies were conducted among predominantly African American women,3-5 whose offspring demonstrate accelerated lung maturation compared with white women.7,8 Thus, the antici-

ated benefits of the new practice guideline

articularly in a pri-

arily white population. We therefore onducted a retrospective study that com- ared short-term maternal and neonatal utcomes before vs after the implementa- ion of the 2007 Practice Bulletin.

ME T H O D S This retrospective, institutional review board– exempt study included all women with a single living nonanomalous fetus who had experienced PPROM at 32 0/7 to 35 6/7 weeks’ gestation from January 1, 2004, to April 1, 2010, and who received care in a single tertiary teaching hospital. A best obstetric estimate of gestational age was determined with the use of menstrual data and first- or second-trimester ultra- sonography. Rupture of membranes was diagnosed by sterile speculum examina- tion that confirmed the pooling of amni- otic fluid in the vagina, positive nitrazine paper test, and positive ferning test. Those women with PPROM in the 3 years before guideline implementation on April 1, 2007, were compared with those with PPROM in the subsequent 3 years with re- gard to maternal and newborn character- istics and outcomes. The primary outcome was composite severe neonatal morbidity (any one of the following occurrences: death, respiratory distress syndrome [RDS],

assisted ventilation for �6 hours, sepsis,

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pneumonia, grade 3 or 4 intraventricular hemorrhage [IVH], or necrotizing entero- colitis). Secondary outcomes included neonatal intensive care unit (NICU) ad- mission, NICU length of stay, respiratory morbidity (RDS or assisted ventilation for �6 hours), and infectious morbidity (cul- ture-proven sepsis or pneumonia).

Women in the “before” group re- ceived inpatient care that consisted of a single course of glucocorticoid therapy at 32 0/7 to 33 6/7 weeks’ gestation, a 2-day course of intravenous ampicillin followed by 5 days of oral amoxicillin, and a single 1-g oral dose of azithromy- cin. Tocolytics were used at physician discretion for up to 48 hours to permit steroid administration. Fetal surveil- lance included daily biophysical profiles and nonstress tests every 4-8 hours. De- livery ensued after spontaneous labor, documentation of fetal lung maturity by the presence of phosphatidylglycerol in amniotic fluid that was obtained from the vaginal pool or by amniocentesis at 32-36 weeks’ gestation, when 35-36 weeks’ gestation was achieved or sooner for nonreassuring fetal status or clinical chorioamnionitis.

Women in the “after” group received identical care, which varied only with re- gard to delivery timing. Again, delivery followed spontaneous labor, nonreas- suring fetal status, or clinical chorioam- nionitis. Alternatively, women in the af-

TABLE 1 Maternal characteristics

Demographic Before

Age, ya 28.4 � ...................................................................................................................

Body mass index, kg/m2a 31.2 � ...................................................................................................................

White, n (%) 103 (96 ...................................................................................................................

Parity, n ..........................................................................................................

0 69 ..........................................................................................................

1 19 ..........................................................................................................

�2 19 ...................................................................................................................

Tobacco use, n (%) 34 (31 ...................................................................................................................

Previous loop electric excision procedure/cone biopsy, n (%)

8 (7.

................................................................................................................... a Data are given as mean � SD.

Faksh. Revised PPROM guideline. Am J Obstet Gynecol 2

ter group were also delivered at 32 0/7 to t

33 6/7 weeks’ gestation if amniotic fluid was obtained from the vaginal pool or by amniocentesis and demonstrated that phosphatidylglycerol was present. If the fluid could not be collected or lung ma- turity was not demonstrated, delivery was initiated at 34 0/7 weeks’ gestation. Finally, delivery was expedited on ad- mission for PPROM after 34 0/7 weeks’ gestation. As of September 2008, a change in NICU admission policy oc- curred, whereby all infants who were born after PPROM �36 0/7 weeks’ ges- tation were admitted to the NICU or intermediate care nursery where they re- mained until hospital discharge. Pre- viously, 35-week infants were triaged in the delivery room based on respiratory status. Infants who were born at �35 0/7 in both time periods routinely were ad- mitted to the NICU; those infants who were born at �36 weeks’ gestation in both time periods were triaged in the de- livery room based on respiratory status.

Maternal characteristics, management, interventions, and outcomes were com- pared by study group. Morbidity included chorioamnionitis (diagnosed by �2 of he following occurrences: maternal fever

38.0°C, uterine tenderness, malodorous aginal discharge, maternal leukocytosis, r fetal tachycardia), postpartum hemor- hage (estimated blood loss �500 mL after vaginal delivery and �1000 mL after a

esarean delivery), postpartum endome-

107) After (n � 64) P value

.8 26.4 � 6.1 .04 ..................................................................................................................

.9 31.5 � 7.9 .81 ..................................................................................................................

62 (96.9) .83 ..................................................................................................................

.66 ..................................................................................................................

39 ..................................................................................................................

15 ..................................................................................................................

10 ..................................................................................................................

22 (34.4) .73 ..................................................................................................................

5 (7.8) .94

..................................................................................................................

ritis (maternal temperature of �38.0°C

OCTOBER 2011 Americ

fter the first 24 postpartum hours with as- ociated uterine tenderness), and wound nfection (periincisional erythema, puru- ent drainage, or induration in the postop- rative period that required antibiotic herapy).

Data were abstracted from the mater- al prenatal record, and the maternal nd newborn inpatient records. Dichot- mous and continuous variables were nalyzed with the chi-square and un- aired t-test, respectively. Logistic and

inear regression analyses were adjusted or covariates. Significance was consid- red for a probability value of � .05.

RE S U L T S One hundred seventy-one eligible subjects were included: 107 women before and 64 women after guideline implementation. Maternal demographics were similar by study group (Table 1). Women who were cared for under the new guideline were less likely to be treated expectantly, despite having experienced PPROM at an earlier average gestational age. They also more of- ten received steroids to accelerate fetal lung maturity. After adjustment for differences in gestational age at PPROM, this group more often had labor induced and deliv- ered on average 1 week earlier than women with PPROM before the new guideline (Table 2). Despite the increased induction rate, primary and total cesarean delivery rates were similar by group. Maternal mor- bidity, including clinical and histologic chorioamnionitis, occurred with similar frequency by study group, except for the later cohort that experienced more post- partum hemorrhages. There were no blood transfusions, however, in any sub- jects (Table 3).

Newborn infant outcomes were ad- justed for differences in gestational age at PPROM and steroid administration. There was no significant difference in the frequency of composite morbidity by time period (Table 4). No infant had a severe IVH or necrotizing enterocolitis. There were 2 cases of suspected intra- uterine growth restriction (estimated fe- tal weight or abdominal circumference �10% for gestational age) in the before group and 1 case in the after group. The

(n �

5 .........

6 .........

.3) .........

.........

.8) .........

.........

only death occurred from disseminated

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herpes infection in a newborn infant of a mother with no history or physical find- ings of infection. Neonates who were born after guideline implementation were more likely to be admitted to the NICU and experience longer NICU stays. These offspring had significantly fewer diagnoses of severe infections, yet no significantly increased rate of respira- tory complications (Table 4). Infants in the before group weighed more than those in the after group (2387 � 373 g vs 2233 � 365 g; P � .009). There was no difference in the frequency of 5-minute Apgar scores of �7 (1.9% vs 4.7%; P � 3).Umbilical arterial cord blood pH was btained in all cases; no infant demon- trated a pH �7.00.

CO M M E N T Our study demonstrates that the imple- mentation of and adherence to recent PPROM management guidelines signif- icantly reduces the composite outcome of neonatal sepsis and pneumonia with- out increasing newborn infant compos- ite morbidity among women who expe- rience PPROM at �32 weeks’ gestation. However, this benefit is associated with significantly more frequent maternal la- bor induction, postpartum hemorrhage, increased NICU use, and a statistically nonsignificant increase in respiratory morbidity. Importantly, the increased induction rate did not raise the primary or overall cesarean delivery rates, and no maternal transfusions were required. The increased NICU use that was ob- served under the new guideline likely re- flects, at least in part, the described change in neonatal admission policy.

These results provide important data regarding the 2007 ACOG PPROM prac- tice bulletin recommendations, particu- larly regarding delivery timing. Several supporting studies that were referenced by the bulletin included mostly urban African American women, who com- prised 55-79.6% of the subjects.3-5 After ontrolling for population differences, reterm infants born to black women ex- erience significantly less hyaline mem- rane disease than those born to white omen on a week-by-week basis from

6-37 weeks.7 Therefore, the generaliz- B

340.e3 American Journal of Obstetrics & Gynecolo

bility of the earlier findings and result- ng practice recommendations to dis- imilar populations remained uncertain. lthough the difference in respiratory orbidity rates between our study

roups was not statistically significant, a arger study population could result in his difference becoming significant. A ost hoc sample size calculation showed hat 257 patients in each group would chieve statistical significance with 80% ower at the .05 level. A recent evaluation of ACOG Practice

TABLE 2 Management of preterm premature

Characteristics Be

Gestational age at PPROM, wka 3 ...................................................................................................................

Gestational age at delivery, wka 3 ...................................................................................................................

Expectant care, n (%) 7 ...................................................................................................................

Latency, da,c ...................................................................................................................

Steroids, n (%) 6 ...................................................................................................................

Antibiotics, n (%) 10 ...................................................................................................................

Tocolytic, n (%) 2 ...................................................................................................................

Amniotic fluid tested for maturity, n (%) 7 ...................................................................................................................

Amniotic fluid test mature, n (%) 3 ...................................................................................................................

Labor induction, n (%) 2 ..........................................................................................................

Indications .................................................................................................

34 wk .................................................................................................

Lung maturity 2 .................................................................................................

Clinical chorioamnionitis .................................................................................................

Nonreassuring fetal status ...................................................................................................................

Cesarean delivery, n (%) ..........................................................................................................

Primary 2 ..........................................................................................................

Total 3 ..........................................................................................................

Indications .................................................................................................

Nonreassuring fetal status 1 .................................................................................................

Malpresentation .................................................................................................

Cephalopelvic disproportion .................................................................................................

Chorioamnionitis .................................................................................................

Repeat .................................................................................................

Elective .................................................................................................

Abruption ...................................................................................................................

PPROM, preterm premature rupture of membranes. a Data are given as mean � SD; b Adjusted for gestational a

expectantly; d Adjusted for gestational age at PPROM and st

Faksh. Revised PPROM guideline. Am J Obstet Gynecol 2

ulletins observed that only 23% of rec-

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mmendations regarding obstetrics top- cs were based on good and consistent vidence (level A).9 The 2007 PPROM ulletin offered 11 recommendations, of hich 5 (45%) were level A. Notably, 2 of recommendations regarding delivery

iming were based on limited and incon- istent scientific data. Moreover, although ractice guidelines should reduce practice ariation and improve health outcomes, ew studies evaluate these intended and otentially unintended consequences of

mplementation.10 Therefore, it is impor-

pture of membranes

e (n � 107) After (n � 64) P value

� 1.0 33.2 � 0.9 .0001 ..................................................................................................................

� 0.9 33.6 � 0.8 .0001b ..................................................................................................................

1.0) 34 (53.1) .02 ..................................................................................................................

� 4.0 4.5 � 3.2 .57 ..................................................................................................................

4.5) 54 (84.4) .004 ..................................................................................................................

00) 63 (98.4) NS ..................................................................................................................

3.4) 11 (17.2) .34 ..................................................................................................................

5.4) 22 (34.3) .001d ..................................................................................................................

4.3) 6 (27.7) .4 ..................................................................................................................

7.1) 35 (54.7) � .0001d ..................................................................................................................

..................................................................................................................

26 ..................................................................................................................

4 ..................................................................................................................

3 ..................................................................................................................

2 ..................................................................................................................

..................................................................................................................

3.4) 15 (23.4) .53 ..................................................................................................................

2.7) 18 (28.1) ..................................................................................................................

..................................................................................................................

8 ..................................................................................................................

4 ..................................................................................................................

2 ..................................................................................................................

1 ..................................................................................................................

2 ..................................................................................................................

0 ..................................................................................................................

t PPROM; c Includes only those patients who were managed s.

for

3.9 .........

4.4 .........

6 (7 .........

4.9 .........

9 (6 .........

7 (1 .........

5 (2 .........

0 (6 .........

1 (4 .........

9 (2 .........

.........

0 .........

6 .........

2 .........

1 .........

.........

5 (2 .........

5 (3 .........

.........

2 .........

9 .........

3 .........

6 .........

1 .........

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populations that are different from those that generated the recommendations, par- ticularly when the recommendations were based on inconsistent supporting evi- dence. Our data confirm the anticipated benefits of less frequent neonatal infec- tious morbidity. However, the results raise questions about the neonatal respiratory consequences of current delivery recom- mendations after PPROM in a 97% white population. The increased frequencies of labor induction and postpartum hemor- rhage also deserve further attention.

Seven randomized trials that have cov- ered a total of 690 subjects have examined expectant vs planned early delivery in

TABLE 3 Maternal morbidity

Outcome Be

Chorioamnionitis, n (%) ..........................................................................................................

Clinical 10 ..........................................................................................................

Histologic 47 ...................................................................................................................

Postpartum hemorrhage, n (%) 5 ...................................................................................................................

Transfusion, n 0 ...................................................................................................................

Endometritis or wound infection, n (%) 4 ...................................................................................................................

Faksh. Revised PPROM guideline. Am J Obstet Gynecol 2

TABLE 4 Neonatal outcomesa

Outcome

Primary, n (%) ..........................................................................................................

Death ..........................................................................................................

Respiratory distress syndrome ..........................................................................................................

Assisted ventilation ..........................................................................................................

Sepsis ..........................................................................................................

Pneumonia ..........................................................................................................

Grade 3/4 intraventricular hemorrhage ..........................................................................................................

Necrotizing enterocolitis ..........................................................................................................

Composite ...................................................................................................................

Secondary ..........................................................................................................

Neonatal intensive care unit .................................................................................................

Admission, n (%) .................................................................................................

Stay, db ..........................................................................................................

Respiratory morbidity, n (%) ..........................................................................................................

Infectious morbidity, n (%) ................................................................................................................... a Adjusted for gestational age at preterm premature rupture o

Faksh. Revised PPROM guideline. Am J Obstet Gynecol 2011.

pregnancies that were complicated by PPROM.3-5,11-14 These studies are difficult o compare with each other and with our nvestigation because of many methodo- ogic differences, such as the time period overed by the study, the gestational ages f included subjects, the administration of ntibiotics and steroids, tocolytic use, the ole of amniotic fluid fetal lung maturity esting in pregnancy management, the iming of planned delivery after PPROM, nd the outcome measures. A recent meta- nalysis of these trials found that planned arly delivery was associated with in- reased rates of labor induction, cesarean elivery, and endometritis but less fre-

e (n � 107) After (n � 64) P value

..................................................................................................................

3) 5 (7.8) .73 ..................................................................................................................

.9) 20 (31.3) .10 ..................................................................................................................

7) 12 (18.8) .003 ..................................................................................................................

0 — ..................................................................................................................

7) 1 (1.6%) .39 ..................................................................................................................

ore (n � 107) After (n � 64) P value

..................................................................................................................

(0.9) 0 .81 ..................................................................................................................

(11.2) 14 (21.9) .23 ..................................................................................................................

(17.8) 21 (32.8) .06 ..................................................................................................................

(4.7) 1 (1.6) .08 ..................................................................................................................

(7.5) 1 (1.6) .14 ..................................................................................................................

0 — ..................................................................................................................

(23.4) 21 (32.8) .42 ..................................................................................................................

..................................................................................................................

(72.9) 62 (96.9) .03 ..................................................................................................................

2 � 3.3 5.0 � 3.2 .05 ..................................................................................................................

(18.9) 21 (32.8) .09 ..................................................................................................................

(11.2) 2 (3.2) .04 ..................................................................................................................

mbranes and steroids; b Data are given as mean � SD.

OCTOBER 2011 Americ

uently with suspected neonatal infection nd newborn infant antibiotic treatment. here were no differences by group re- arding perinatal, neonatal, or intrauterine etal deaths or morbidities of IVH or RDS. nterestingly, frequencies of chorioamnio- itis, positive neonatal blood cultures, and neumonia were not significantly different y management approach. The authors oncluded that insufficient evidence exists o guide clinical decision-making regard- ng immediate delivery vs expectant man- gement of PPROM, citing inadequate sta- istical power.1

A prospective cohort study compared neonatal outcomes after expectant vs elec- tive delivery of PPROM between 24 0/7 to 33 6/7 weeks’ gestation. Similar to our management, antepartum care included antibiotics and steroids. As in the current report, the frequency of RDS was statisti- cally similar in both groups, although sep- sis was less frequent with elective delivery. Contrasting our findings, a significant re- duction in the rate of grade 3 or 4 IVH led to a decrease in severe composite morbid- ity among electively delivered infants, probably related to the earlier gestational ages of included PPROM subjects. This group also had a higher cesarean delivery rate, which reflected the increased inci- dence of nonvertex presenting fetuses, again likely a consequence of early gesta- tional ages at membrane rupture.2

A retrospective investigation of pa- tients who experience PPROM at �24 weeks’ gestation and who delivered at �37 weeks’ gestation from 1998-2000 examined maternal and neonatal com- plications to determine an ideal gesta- tional age for delivery. Steroids and broad-spectrum antibiotics were admin- istered routinely. If phosphatidylglycerol was present in vaginal pool fluid at �32 weeks’ gestation, delivery was expedited. When compared with pregnancies with PPROM delivery at 36 0/7 to 36 6/7 weeks’ gestation, major and minor composite neonatal morbidity were increased among those infants who were delivered at �33 and �34 weeks’ gestation, respectively.

he authors questioned the benefit of ex- ectant management of PPROM at �34 eeks’ gestation.15

The limited short-term neonatal bene-

for

.........

(9. .........

(43 .........

(4. .........

.........

(3. .........

Bef

.........

1 .........

12 .........

19 .........

5 .........

8 .........

0 .........

25 .........

.........

78 .........

3. .........

20 .........

12 .........

f me

fits of expectant management of PPROM

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that were noted in the current and earlier studies likely reflect several factors. Con- temporary maternal and neonatal care that features antepartum steroids, broad-spec- trum antibiotics, selective tocolytic use, and improved NICU care are probable contributors to the observed outcomes. Additionally, the relatively short latency period that is anticipated with expectant care of PPROM at �34 weeks’ gestation may be insufficient to favorably impact short-term neonatal outcomes. One re- port noted latencies at �48 hours in only 0.4% of such cases.16 Another article de- cribed a mean latency of 2.4 � 3.1 days mong these women.15 The similarly short

mean latency intervals that we observed, coupled with later mean gestational ages of PPROM that were studied, support this explanation.

Chorioamnionitis and the accompa- nying inflammatory response have been implicated in adverse long-term neuro- logic sequelae among exposed offspring.17

An important rationale for the active man- agement of PPROM is to minimize the risks that are associated with such expo- sures. However, contrasting most previous studies, we found no differences in the rates of clinical or histologic chorioamnio- nitis between expectantly and actively managed PPROM.3,4,5,11 We suspect that

ur findings reflect the shorter latencies nd less frequent inflammation that are oted with PPROM at later gestational ges, such as those included in our study.18

This observation is strengthened by the availability of placental pathologic findings for all subjects in both time periods of our study.

Our report offers several strengths be- yond those already mentioned. Data were drawn from a single institution with 1 ma- ternal fetal medicine group and 1 neona- tology group providing consistent patient care. One institutional guideline for ante- partum care was in effect for each time pe- riod. No obstetrical practice changes other than delivery timing resulted from guide- line implementation. Neonatal practice changed only with regard to the described admission policy. Therefore, we believe that the observed results, with the possible exception of NICU use, likely stem from the revised delivery policy. We recognize

several limitations, including the retro-

340.e5 American Journal of Obstetrics & Gynecolo

spective study design and population differences among subjects in the 2 time periods that were examined. However, re- gression analyses adjusted for differences in confounders between the 2 groups. Be- cause the patients were drawn from a ter- tiary referral center, the data may not re- flect population-based rates of the various outcome measures. Although the homo- geneity of our population was a strength in addressing our research question, it may limit generalizability of our results to dis- similar patients.

In summary, the implementation of the 2007 ACOG PPROM Practice Bulletin guidelines in our population significantly reduced severe neonatal infectious mor- bidity without significantly exacerbating composite morbidity. However, these benefits must be balanced against in- creased induction and hemorrhage rates, coupled with concerns for increased neo- natal respiratory morbidity. We also ob- served increased intensive care use, even after adjusting for earlier gestational age at PPROM and increased steroid use, which may reflect changes in neonatal admission policy. Additional research should also evaluate the cost-effectiveness of imple- mentation of the guideline’s recommen- dations and the subsequent impact on long-term childhood pulmonary, neuro- logic, and developmental sequelae. A ran- domized trial of expectant vs active man- agement of PPROM at �32 weeks’ gestation would shed important light on these uncertainties. f

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Martin RW, Morrison JC. Premature rupture of

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membranes at 34 to 37 weeks’ gestation: aggressive versus conservative management. Am J Obstet Gynecol 1998;178:126-30. 5. Cox SM, Leveno KJ. Intentional delivery ver- sus expectant management with preterm rup- tured membranes at 30-34 weeks’ gestation. Obstet Gynecol 1995;86:875-9. 6. American College of Obstetricians and Gyne- cologists. Premature rupture of membranes: ACOG practice bulletin no. 80. Obstet Gynecol 2007;109:1007-19. 7. Hulsey TC, Alexander GR, Robillard PY, Anni- bale DJ, Keenan A. Hyaline membrane disease: the role of ethnicity and maternal risk characteris- tics. Am J Obstet Gynecol 1993;168:572-6. 8. Richardson DK, Torday JS. Racial differences in predictive value of the lecithin/sphingomyelin ratio. Am J Obstet Gynecol 1994;170:1273-8. 9. Chauhan SP, Berghella V, Sanderson M, Magann EF, Morrison JC. American College of Obstetricians and Gynecologists practice bulle- tins: an overview. Am J Obstet Gynecol 2006; 194:1564-75. 10. Shackelton RJ, Marceau CD, Link CL, McKinlay JB. The intended and unintended consequences of clinical guidelines. J Eval Clin Pract 2009;15:1035-42. 11. Spinnato JA, Shaver DC, Bray EM, Lipshitz J. Preterm premature rupture of the membranes with fetal pulmonary maturity present: a prospec- tive study. Obstet Gynecol 1987;69:196-201. 12. Garite TJ, Freeman RK, Linzey EM, Braley PA, Dorchester WL. Prospective randomized study of corticosteroids in the management of premature rupture of the membranes and the premature gestation. Am J Obstet Gynecol 1981;141:508-15. 13. Iams JD, Talbert ML, Barrows H, Sacks L. Management of preterm prematurely ruptured membranes: a prospective randomized com- parison of observation versus use of steroids and timed delivery. Am J Obstet Gynecol 1985;151:32-8. 14. Nelson LH, Meis PJ, Hatjis C, Ernest JM, Dillard R, Schey HM. Premature rupture of membranes: a prospective, randomized evalu- ation of steroids, latent phase, and expectant management. Obstet Gynecol 1985;66:55-8. 15. Lieman JM, Brumfield CG, Carlo W, Ram- sey PS. Preterm premature rupture of mem- branes: is there an optimal gestational age for delivery? Obstet Gynecol 2005;105:12-7. 16. Neerhof MG, Cravello C, Haney EI, Silver RK. Timing of labor induction after premature rupture of membranes between 32 and 36 weeks’ ges- tation. Obstet Gynecol 1999:180:349-52. 17. Shatrov JG, Birch SC, Lam LT, Quinlivin JA, McIntyre S, Mendz GL. Chorioamnionitis and cerebral palsy: a meta-analysis. Obstet Gynecol 2010;116:387-92. 18. Ramsey PS, Lieman JM, Brumfield CG, Carlo W. Chorioamnionitis increases neonatal morbidity in pregnancies complicated by pre- term premature rupture of membranes. Am J

Obstet Gynecol 2005;192:1162-6.

Preterm premature rupture of membranes ≥32 weeks` gestation: impact of revised practice g ...

Methods
Results
Comment
References