Objective
Pregnancy hypertension is a leading cause of maternal and perinatal mortality and morbidity. Between 34 +0 and 36 +6 weeks gestation, it is uncertain whether planned delivery could reduce maternal complications without serious neonatal consequences. In this individual participant data meta-analysis, we aimed to compare planned delivery to expectant management, focusing specifically on women with preeclampsia.
Data Sources
We performed an electronic database search using a prespecified search strategy, including trials published between January 1, 2000 and December 18, 2021. We sought individual participant-level data from all eligible trials.
Study Eligibility Criteria
We included women with singleton or multifetal pregnancies with preeclampsia from 34 weeks gestation onward.
Methods
The primary maternal outcome was a composite of maternal mortality or morbidity. The primary perinatal outcome was a composite of perinatal mortality or morbidity. We analyzed all the available data for each prespecified outcome on an intention-to-treat basis. For primary individual patient data analyses, we used a 1-stage fixed effects model.
Results
We included 1790 participants from 6 trials in our analysis. Planned delivery from 34 weeks gestation onward significantly reduced the risk of maternal morbidity (2.6% vs 4.4%; adjusted risk ratio, 0.59; 95% confidence interval, 0.36–0.98) compared with expectant management. The primary composite perinatal outcome was increased by planned delivery (20.9% vs 17.1%; adjusted risk ratio, 1.22; 95% confidence interval, 1.01–1.47), driven by short-term neonatal respiratory morbidity. However, infants in the expectant management group were more likely to be born small for gestational age (7.8% vs 10.6%; risk ratio, 0.74; 95% confidence interval, 0.55–0.99).
Conclusion
Planned early delivery in women with late preterm preeclampsia provides clear maternal benefits and may reduce the risk of the infant being born small for gestational age, with a possible increase in short-term neonatal respiratory morbidity. The potential benefits and risks of prolonging a pregnancy complicated by preeclampsia should be discussed with women as part of a shared decision-making process.
Why was this study conducted?
There is limited evidence regarding the optimal timing of delivery in late preterm preeclampsia, and single studies have not produced robust conclusions.
Key findings
Planned delivery from 34 weeks onward in women with preeclampsia significantly reduces maternal morbidity (adjusted risk ratio [RR], 0.59; 95% confidence interval [CI], 0.36–0.98) and the incidence of infants born small for gestational age (RR, 0.74; 95% CI, 0.55–0.99) but increases short-term neonatal respiratory morbidity (adjusted RR, 1.22; 95% CI, 1.01–1.47). The risk of short-term neonatal respiratory morbidity was lower in more recent trials where the use of antenatal steroids was higher.
What does this add to what is known?
This is the first individual patient data meta-analysis to evaluate planned delivery in women with preeclampsia at late preterm gestations. We have quantified the effect of planned delivery from 34 weeks onward on infant outcomes more precisely, demonstrating a reduction in the risk of infants being born small for gestational age but an increase in short-term neonatal respiratory morbidity. Evidence to guide clinical practice in this area is lacking. Our analysis provides more accurate information on the risks and benefits of planned delivery for preeclampsia without severe features from 34 weeks onward.
Introduction
Pregnancy hypertension is responsible for at least 27,800 maternal deaths worldwide every year and 500,000 infant deaths, including approximately 200,000 stillbirths. Although the prevalence of preeclampsia varies throughout the world, it complicates between 2% and 3% of pregnancies in a high-income setting. Estimates for low- and middle-income countries are higher, with up to 12% of pregnancies affected in these settings. Delivery is the only definitive management for this progressive and unpredictable condition, and it is routinely recommended for all women with preeclampsia from 37 weeks gestation onward. At gestations up to 34 weeks, if there are no immediate indications for delivery, expectant management is preferable because of the neonatal risks associated with early preterm birth.
It is less clear whether a policy of expectant management in the late preterm period (34–37 weeks) should be pursued, although if severe features of preeclampsia develop or the woman reaches 37 weeks, delivery is indicated. However, there is uncertainty as to whether a policy of routine immediate delivery at this gestational window (34–37 weeks) could reduce maternal complications without serious neonatal consequences. Several studies have compared these 2 strategies in women with hypertensive disorders of pregnancy (including preeclampsia) from 34 weeks. However, it has not been possible to draw firm conclusions from individual studies alone. Recent meta-analyses , and individual participant data (IPD) meta-analyses of women with hypertensive disorders of pregnancy have shown that planned early delivery from 34 weeks gestation reduces maternal complications, but the neonatal impact remains unclear. These reviews generally grouped all hypertensive disorders of pregnancy together, combining women with chronic hypertension, gestational hypertension, and preeclampsia. However, the underlying pathophysiology of preeclampsia is distinct, with maternal endothelial dysfunction leading to multiorgan complications and potentially severe maternal and fetal outcomes. The optimal timing of delivery in preeclampsia may therefore differ compared with other hypertensive disorders of pregnancy, and the balance of risks and benefits for the infant should also be considered within the context of this rapidly progressive and unpredictable disease. A limited subgroup analysis conducted as part of the previous IPD meta-analysis in women with all types of pregnancy hypertension identified women with preeclampsia as a population in whom planned delivery may confer significant benefit. The authors therefore highlighted a need to evaluate the impact of this intervention specifically in women with preeclampsia. Since this meta-analysis was published, a new trial has been reported, enrolling more women with preeclampsia than all previously included trials combined. This enabled us to conduct an IPD meta-analysis evaluating the timing of delivery on a wider set of maternal and perinatal outcomes in this high-risk group of women with preeclampsia. A meta-analysis evaluating early delivery or expectant management for late preterm preeclampsia was recently published. However, this study was limited by its inclusion of just 3 randomized controlled trials, only 2 of which were used to evaluate the coprimary outcome of neonatal intensive care unit admission. Our IPD meta-analysis is strengthened by its ability to harmonize data to overcome inconsistencies in outcome definitions between trials and to evaluate key outcomes such as neonatal morbidity, in more detail.
Objective
The objective of this study was to undertake an IPD meta-analysis focusing on women with preeclampsia alone. In women with preeclampsia from 34 weeks gestation onward, this study aimed to evaluate the effect of planned early delivery on maternal mortality or morbidity and perinatal mortality or morbidity compared with expectant management using IPD from randomized controlled trials. The use of IPD enabled us to target our review to women with late preterm preeclampsia and to perform subgroup analyses and adjustments that would not be possible with the use of aggregate data, for example, using blood pressure values to reflect the severity of disease. This is clinically relevant, because the presence of additional risk factors in women with preeclampsia may alter management options.
Methods
Search strategy and study selection
We followed a protocol and statistical analysis plan published in the PROSPERO registry in accordance with PRISMA-IPD guidance. We included studies that were randomized controlled trials comparing planned early delivery with expectant management in women presenting with preeclampsia from 34 weeks gestation onward. Cluster randomized trials or studies with a quasi-randomized design were excluded. To identify the eligible studies, we electronically searched the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, MEDLINE, and ClinicalTrials.gov using the search terms “pre-eclampsia” OR “preeclampsia” AND “delivery” OR “birth” with the limits “human” and “randomized controlled trial.” The final search date was December 18, 2021. We did not restrict our search by language. We excluded trials published before the year 2000. This was because of changes in clinical practice, care of women with preeclampsia, and neonatal care over time such that the findings from earlier trials may be difficult to interpret. To ensure that the search was comprehensive, we also hand-searched the reference lists of the retrieved studies and any relevant reviews identified. Two independent review authors (A.B.G. and J.F.) assessed all the studies identified by the search strategy against the study-level inclusion criteria. Any disagreement was resolved through discussion or with a third review author (not required), if necessary.
Eligibility criteria
We included women with singleton or multifetal pregnancies presenting with preeclampsia or superimposed preeclampsia from 34 weeks gestation onward. The definition of preeclampsia or superimposed preeclampsia was that used by the study at the time. All the definitions used would now be encompassed by the current International Society for the Study of Hypertension in Pregnancy (ISSHP) 2018 diagnostic criteria.
Data extraction
We sought participant-level data from the authors of all eligible trials. The available data were extracted from trial databases (provided via a data-sharing agreement) according to prespecified variables by 2 of the review authors (A.B.G. and P.S.). The data were recoded into a common format, and the definitions of key characteristics, diagnoses (eg, preeclampsia), and outcomes were harmonized. A final dataset was then produced and rechecked for accuracy and completeness.
Assessment of risk of bias
Two review authors (A.B.G. and J.F.) independently assessed the included trials for risk of bias using the Cochrane risk-of-bias tool.
Outcomes
The primary maternal outcome was a composite of maternal mortality and severe maternal morbidity (adapted from a previously published composite derived by Delphi consensus). The presence of severe maternal morbidity was defined as 1 or more of the following individual components: maternal death, eclampsia, stroke, pulmonary edema, HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome, acute renal insufficiency, and placental abruption. The primary perinatal outcome was a composite of perinatal mortality or morbidity. This was defined as any 1 of perinatal death, neonatal death, or neonatal morbidity. The selection of components was guided by recent recommendations for core outcome sets in preeclampsia. Neonatal morbidity was defined as 1 or more of respiratory disease (any one of respiratory distress syndrome, need for respiratory support, neonatal unit admission for respiratory disease or bronchopulmonary dysplasia), central nervous system complications (any 1 of intraventricular hemorrhage, intracerebral hemorrhage, periventricular leukomalacia, hypoxic ischemic encephalopathy, cerebral infarction, or convulsions), culture-proven sepsis, necrotizing enterocolitis, hypoglycemia requiring intravenous glucose or neonatal unit admission, or jaundice requiring neonatal unit admission. If data were missing (ie, not collected for a particular component) for either of the composite outcomes, we treated it as absent. The secondary maternal outcomes included severe postpartum hemorrhage, progression to severe hypertension, thromboembolic disease, hepatic dysfunction, onset of delivery, and admission to maternal intensive care unit. The secondary perinatal outcomes were gestational age at delivery, mode of delivery, birthweight, birthweight centile, baby sex, small for gestational age (<3rd centile or <10th centile), admission to neonatal unit, admission to neonatal intensive care unit, 5-minute Apgar score <7, and arterial pH <7.05.
Data synthesis
We analyzed all available data for baseline maternal characteristics at enrolment, related process outcomes (such as time from randomization to delivery) and the data for each prespecified outcome on an intention-to-treat basis. In each study, all the outcomes of interest were either reported completely with <5% missingness or not reported at all. Under these circumstances, multiple imputation is not feasible or recommended, and we therefore analyzed all the outcomes without imputation. For primary IPD meta-analyses, we used a 1-stage fixed-effect model. Standard errors, confidence intervals (CIs), and P values were adjusted for clustering within studies. In addition, we used robust standard errors to correct for clustering of twin pregnancies by the mother for the perinatal outcomes. We set out to calculate the odds ratios using multilevel models as originally outlined in the statistical analysis plan. However, this multilevel model structure did not converge, as there were not sufficient datapoints at each of the levels. We therefore performed a multivariate analysis, calculating risk ratios for binary outcomes and mean differences for continuous outcomes using a simpler fixed-effects model. We also calculated unadjusted risk differences. A fixed-effects, 1-stage analysis such as this is appropriate where there are small studies with rare event numbers. We gave a separate intercept for each trial but assumed the same treatment effect (ie, we used fixed effects for each trial).
The numbers needed to treat or harm with 95% CIs were calculated for outcomes where a significant difference between the management groups was found. The analysis was adjusted for study, gestational age at randomization (34 +0 –34 +6 weeks, 35 +0 –35 +6 weeks, 36 +0 –36 +6 weeks, 37 +0 –37 +6 weeks, 38 +0 –38 +6 weeks, 39 +0 –39 +6 weeks, 40 +0 weeks and above), severity of systolic hypertension at study entry (<150 vs ≥ 150 mm Hg), parity (primiparous vs multiparous), and number of fetuses (singleton vs all other). The severity of systolic hypertension at study entry was chosen, because it is an objective marker of disease severity consistently available across studies, and there is a known dose–response relationship between increasing blood pressure and adverse pregnancy outcomes. We calculated and used the average value (or proportion for categorical variables) across all studies, where these prespecified adjustment variables were missing. We did not use multiple imputation methods, as they are not recommended in this scenario. Subgroup analysis was conducted if there were at least 10 events in each subgroup; this was also done using a 1-stage, fixed-effects model. The prespecified subgroups were study, gestational age at randomization, parity, singleton vs multifetal pregnancy, previous cesarean delivery, prerandomization diabetes of any type, superimposed preeclampsia, and suspected fetal growth restriction at enrolment. Because many of the subgroups concerned the same adjustment variables used for our main analysis (including some additional subgroups of clinical relevance), our subgroup analysis was unadjusted to better delineate the effect of these variables. Heterogeneity was assessed using I 2 (the proportion of the total variance of the outcome that is between studies rather than between subjects within studies) as part of the subgroup analysis. We have also presented values for tau. No additional analyses were undertaken. This IPD meta-analysis was prospectively registered with PROSPERO ( https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020206425 ).
Results
Study selection
We identified 1617 references after duplicates were removed ( Figure 1 ). A total of 1567 references were excluded after title screening, and 43 were excluded after abstract and full-text screening. Seven trials (3791 participants) were considered eligible for inclusion at study-level. One trial (100 participants) was subsequently excluded, as the trial authors did not respond to our request for participant-level data despite several attempts. The only published data available from this trial were a conference abstract, and therefore we were not able to include any aggregate data for this trial. Six trials with participant-level data were available. Following data extraction and review by 2 authors, 1901 participants were deemed ineligible for inclusion in this IPD meta-analysis principally because of women being enrolled with conditions other than preeclampsia or before 34 weeks gestation, with the reasons given for exclusion in Table 1 . The remaining 1790 participants from 6 trials were therefore included in our analysis.
| Study | Setting | Total participants enrolled (n) | Trial participants (inclusion criteria) | Eligible for IPD (n) | Noneligible for IPD (n) | ||
|---|---|---|---|---|---|---|---|
| Gestational age (wk) | Singleton or twin pregnancy | Diagnosis | |||||
| GRIT GRIT Study Group, 2003 | 69 hospitals in 13 European countries | 548 planned delivery n=296, expectant management=292 | 24 +0 to 36 +0 | Singleton or twin | Fetal compromise with an umbilical artery Doppler waveform recorded (including pregnancies complicated by preeclampsia) | 15 planned delivery n=15, expectant management n=5 | 493 randomized before 34 wk; 40 no preeclampsia at study entry |
| HYPITAT Koopmans et al, 2009 | 38 hospitals in The Netherlands | 756 planned delivery n=377, expectant management=379 | 36 +0 to 41 +0 | Singleton | Gestational hypertension or preeclampsia without severe features a | 246 planned delivery n=123, expectant management n=123 | 510 no preeclampsia at study entry |
| DIGITAT Boers et al, 2010 | 52 hospitals in The Netherlands | 650 planned delivery n=321, expectant management n=329 | 36 +0 to 41 +0 | Singleton | Suspected intrauterine growth restriction (including pregnancies complicated by preeclampsia) | 45 planned delivery, n=18, expectant management n=27 | 605 no preeclampsia at study entry |
| Deliver or Deliberate Owens et al, 2014 | 1 hospital in the United States | 169 planned delivery n=97, expectant management n=86 | 34 +0 to 36 +6 | Singleton or twin | Preeclampsia (ACOG 2002 criteria) without any other maternal-fetal complications | 165 planned delivery, n=93, expectant management n=72 | 4 randomized before 34 wk |
| HYPITAT II Broekhuijsen et al, 2015 | 51 hospitals in The Netherlands | 703 planned delivery n=352, expectant management, n=351 | 34 +0 to 36 +6 | Singleton or twin | Any hypertensive disorder of pregnancy without severe features a | 420 planned delivery n=209, expectant management n=211 | 4 randomized before 34 wk; 283 no preeclampsia at study entry |
| PHOENIX Chappell et al, 2019 | 46 hospitals in England and Wales | 901 planned delivery n=450, expectant management n=451 | 34 +0 to 36 +6 | Singleton or twin | Preeclampsia (ISSHP 2014 criteria), not requiring immediate delivery | 899 planned delivery, n=448, expectant management n=451 | 2 withdrew from trial |
a Preeclampsia defined as a diastolic blood pressure of 90 mm Hg or higher measured on 2 occasions at least 6 hours apart, combined with proteinuria.
Study characteristics
A summary of characteristics of included studies, including details of the interventions, can be found in Table 1 and Supplementary Tables S1 and S2 . Two trials (GRIT and DIGITAT) enrolled women with suspected fetal growth restriction on ultrasound, including those with pregnancies complicated by preeclampsia, over a wide gestational age range. The HYPITAT and HYPITAT II trials enrolled women with any hypertensive disorder of pregnancy from 36 +0 and 34 +0 weeks gestation onward, respectively. The PHOENIX trial and Deliver or Deliberate trial focused specifically on women with preeclampsia (without severe features) between 34 +0 and 36 +6 weeks gestation. None of the trials enrolled women with severe features of preeclampsia or any other indications for immediate delivery. This was stated in each of their inclusion criteria ( Table 1 ), with severe features defined in accordance with the relevant guidelines at the time (primarily American College of Obstetricians and Gynecologists or ISSHP criteria). These are consistent with current definitions. For the purposes of this IPD meta-analysis, we selected only those participants who met our eligibility criteria as described in the section above.
Risk of bias of included studies
The results of our risk of bias assessment using the Cochrane Risk of Bias 2 tool can be found in Figures 2 and 3 . The PHOENIX and HYPITAT trials were prospectively registered in a clinical trials registry (before enrolment of the first participants). The GRIT, DIGITAT, Deliver or Deliberate, and HYPITAT II trials were retrospectively registered. Four of the included trials were assessed as being at a low risk of bias. The HYPITAT II trial had some concerns because of minor discrepancies between the published protocol and final paper. The Deliver or Deliberate trial was judged to be at a high risk of bias. This was primarily because of limited reporting regarding the randomization process and an imbalance in the final analysis population suggesting postrandomization exclusions. Supplementary Tables S3 and S4 describe the missing data for each maternal and perinatal variable by study. Missing data were usually because of the outcome not being collected, with very few cases of missing data because of incomplete reporting or exclusion.
Synthesis of results
The baseline maternal characteristics at enrolment were similar across the planned delivery and expectant management groups ( Table 2 ). Importantly, the proportion of women with suspected fetal growth restriction and severe hypertension at enrolment ( Table 2 ) was balanced between the 2 management groups as expected with randomization. None of the trials enrolled women with severe features of preeclampsia. However, we acknowledge that some participants may have transiently had high blood pressure readings before enrolment. This alone would not be an indication for delivery. The difference in median time between the 2 groups from randomization to delivery was 4.0 (95% CI, 3.0–4.0) days. One-stage meta-analysis found that planned delivery from 34 weeks gestation onward significantly reduced the risk of major maternal morbidity (2.6% vs 4.4%; adjusted risk ratio [aRR], 0.59; 95% CI, 0.36–0.98; P =.041) compared with expectant management ( Table 3 ). This direction of effect was also consistent across the secondary maternal outcomes ( Table 4 ), with a significant reduction in postrandomization severe hypertension (risk ratio [RR], 0.80; 95% CI, 0.73–0.87). The primary composite perinatal outcome of perinatal mortality (stillbirth or early neonatal death) or morbidity was increased by planned delivery (20.9% vs 17.1%; aRR, 1.22; 95% CI, 1.01–1.47; P =.040). This result was driven by a significant increase in neonatal respiratory disease (RR, 1.41; 95% CI, 1.05–1.90) ( Table 5 ). Neonatal unit admission was also increased among infants born to mothers in the planned delivery arm (RR, 1.21; 95% CI, 1.08–1.36) ( Table 6 ). However, infants in the planned delivery group were less likely to be born small for gestational age, both <3rd centile (RR, 0.74; 95% CI, 0.55–0.99) and <10th centile (RR, 0.82; 95% CI, 0.70–0.97). As expected, given the nature of the intervention, there was an adjusted mean difference of −0.61 weeks in the gestational age at delivery between infants in the planned delivery and expectant management groups and an adjusted mean difference of −127.28 g in birthweight between the 2 groups ( Table 6 ). There was no significant difference in vaginal delivery between the planned delivery and expectant management groups. The observed difference in the primary perinatal outcome between the allocated groups was largely driven by a difference in respiratory distress syndrome, seen mainly in infants from trials conducted earlier in the time period (the HYPITAT II trial between 2009 and 2013 and the Deliver or Deliberate trial between 2002 and 2008). The individual components of the respiratory disease composite outcome by study are shown in Supplementary Table S5 . Overall, there were small numbers of central nervous system complications (individual components of this composite outcome by study are shown in Supplementary Table S6 ), with babies from the earlier HYPITAT II and GRIT trials (conducted between 1993 and 2001) contributing to most of the cases. The subgroup analyses ( Figures 4 and 5 ) were consistent with the main results. Higher degrees of heterogeneity were seen when analyzed by study and by twin or singleton pregnancy. Subgroup analysis was only undertaken if there were 10 or more events in each subgroup, which meant that the overall effect by study was different to that reported for the overall IPD meta-analysis because of the exclusion of certain trials from the subgroup analysis. A summary of findings and the numbers need to treat and harm are presented in supplementary tables S9 and S10 .
| Characteristic | n | Planned delivery n=901 | n | Expectant management n=889 |
|---|---|---|---|---|
| Maternal age (y; mean [SD]) | 901 | 29.56 (6.32) | 889 | 29.97 (6.12) |
| White European ethnicity | 891 | 618 (69.4) | 884 | 624 (70.6) |
| No previous births | 891 | 564 (63.3) | 884 | 555 (62.8) |
| Singleton pregnancy | 901 | 866 (96.1) | 889 | 843 (94.8) |
| Previous cesarean delivery | 780 | 99 (12.7) | 785 | 101 (12.9) |
| Prerandomization diabetes | 780 | 94 (12.1) | 785 | 88 (11.2) |
| Suspected fetal growth restriction | 808 | 124 (15.3) | 817 | 132 (16.2) |
| Systolic blood pressure≥160 mm Hg | 810 | 227 (28.0) | 818 | 221 (27.0) |
| Systolic blood pressure≥150 mm Hg | 810 | 442 (54.6) | 818 | 433 (52.9) |
| Diagnosis of superimposed preeclampsia | 675 | 100 (14.8) | 689 | 113 (16.4) |
| Individual components | |||
|---|---|---|---|
| Maternal death | 0/891 (0.0) | 1/884 (0.1) c | — |
| Eclampsia | 3/891 (0.3) | 6/884 (0.7) | RR, 0.50 (0.12–1.98) |
| Stroke | 0/559 (0.0) | 0/550 (0.0) | — |
| Pulmonary edema | 1/798 (0.1) | 4/812 (0.5) | RR, 0.25 (0.03–2.27) |
| HELLP syndrome | 12/891 (1.3) | 23/884 (2.6) | RR, 0.52 (0.26–1.03) |
| Renal insufficiency | 4/768 (0.5) | 6/761 (0.8) | RR, 0.66 (0.19–2.33) |
| Placental abruption | 4/768 (0.5) | 4/812 (0.5) | RR, 1.02 (0.26–4.05) |
a Effect sizes are RRs (95% CIs) unless stated otherwise
b aRR for study, gestational age at randomization, singleton pregnancy, parity, and severity of hypertension at study entry. Presented as unadjusted RR where the model failed to converge
c This death was considered unrelated to trial allocation by the original study authors.
| Outcome | Planned delivery n=891 | Expectant management n=884 | Effect size a |
|---|---|---|---|
| Postrandomization severe hypertension | 396/780 (50.8) | 498/785 (63.4) | RR, b 0.80 (0.73– 0.87) |
| Hepatic dysfunction | 72/891 (8.1) | 96/884 (10.9) | aRR, 0.76 (0.57–1.01) |
| Thromboembolic disease | 1/798 (0.1) | 1/812 (0.1) | — |
| Severe postpartum hemorrhage | 87/891 (9.8) | 98/884 (11.1) | aRR, 0.88 (0.68–1.15) |
| Prelabor cesarean delivery | 156/797 (19.6) | 180/811 (22.2) | RR, 0.88 (0.73–1.07) |
| Intensive care unit admission | 9/589 (1.5) | 19/601 (3.2) | aRR, 0.48 (0.22–1.07) |
| Time from randomization to delivery (d), Median (IQR) | 2.0 (1.0–3.0) n=890 c | 6.0 (3.0–10.0) n=883 c | Difference (95% CI) 4.0 (3.0–4.0) |
a Effect sizes are RRs (95% CIs) unless stated otherwise
b aRR for study, gestational age at randomization, singleton pregnancy, parity, and severity of hypertension at study entry. Presented as unadjusted RR where model failed to converge
c One woman (from each group) excluded because of missing gestational age at delivery.
| Individual components | Planned delivery | Expectant management | RR |
|---|---|---|---|
| Stillbirth | 0/936 (0.0) | 0/935 (0.0) | — |
| Neonatal death | 1/936 (0.1) | 0/935 (0.0) | RR, 1.00 (1.00–1.00) |
| Respiratory disease | 95/936 (10.1) | 66/935 (7.1) | RR, 1.41 (1.05–1.90) |
| Central nervous system complications | 11/936 (1.2) | 4/935 (0.4) | RR, 2.65 (0.90–7.83) |
| Neonatal sepsis | 3/489 (0.6) | 2/502 (0.4) | RR, 1.54 (0.26–9.20) |
| Necrotizing enterocolitis | 3/936 (0.3) | 0/935 (0.0) | RR, 1.00 (1.00–1.00) |
| Hypoglycemia | 86/692 (12.4) | 86/708 (12.1) | RR, 1.03 (0.77–1.37) |
| Jaundice | 19/612 (3.1) | 13/625 (2.1) | RR, 1.56 (0.78–3.11) |
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