Induction of labour versus expectant monitoring for gestational hypertension or mild pre-eclampsia after 36 weeks' gestation (HYPITAT): a multicentre, open-label randomised controlled trial

BACKGROUND

Robust evidence to direct management of pregnant women with mild hypertensive disease at term is scarce. We investigated whether induction of labour in women with a singleton pregnancy complicated by gestational hypertension or mild pre-eclampsia reduces severe maternal morbidity.

METHODS

We undertook a multicentre, parallel, open-label randomised controlled trial in six academic and 32 non-academic hospitals in the Netherlands between October, 2005, and March, 2008. We enrolled patients with a singleton pregnancy at 36-41 weeks' gestation, and who had gestational hypertension or mild pre-eclampsia. Participants were randomly allocated in a 1:1 ratio by block randomisation with a web-based application system to receive either induction of labour or expectant monitoring. Masking of intervention allocation was not possible. The primary outcome was a composite measure of poor maternal outcome--maternal mortality, maternal morbidity (eclampsia, HELLP syndrome, pulmonary oedema, thromboembolic disease, and placental abruption), progression to severe hypertension or proteinuria, and major post-partum haemorrhage (>1000 mL blood loss). Analysis was by intention to treat and treatment effect is presented as relative risk. This study is registered, number ISRCTN08132825.

FINDINGS

756 patients were allocated to receive induction of labour (n=377 patients) or expectant monitoring (n=379). 397 patients refused randomisation but authorised use of their medical records. Of women who were randomised, 117 (31%) allocated to induction of labour developed poor maternal outcome compared with 166 (44%) allocated to expectant monitoring (relative risk 0.71, 95% CI 0.59-0.86, p<0.0001). No cases of maternal or neonatal death or eclampsia were recorded.

INTERPRETATION

Induction of labour is associated with improved maternal outcome and should be advised for women with mild hypertensive disease beyond 37 weeks' gestation.

FUNDING

ZonMw.

Incidence, risk factors, and temporal trends in severe postpartum hemorrhage

OBJECTIVE

Because the diagnosis of postpartum hemorrhage (PPH) depends on the accoucheur's subjective estimate of blood loss and varies according to mode of delivery, we examined temporal trends in severe PPH, defined as PPH plus receipt of a blood transfusion, hysterectomy, and/or surgical repair of the uterus.

STUDY DESIGN

We analyzed 8.5 million hospital deliveries in the US Nationwide Inpatient Sample from 1999 to 2008 for temporal trends in, and risk factors for, severe PPH, based on International Classification of Diseases, 9th revision, clinical modification diagnosis and procedure codes. Sequential logistic regression models that account for the stratified random sampling design were used to assess the extent to which changes in risk factors explain the trend in severe PPH.

RESULTS

Of the total 8,571,209 deliveries, 25,906 (3.0 per 1000) were complicated by severe PPH. The rate rose from 1.9 to 4.2 per 1000 from 1999 to 2008 (P for yearly trend < .0001), with increases in severe atonic and nonatonic PPH, due especially to PPH with transfusion, but also PPH with hysterectomy. Significant risk factors included maternal age ≥35 years (adjusted odds ratio [aOR], 1.5; 95% confidence interval [CI], 1.5-1.6), multiple pregnancy (aOR, 2.8; 95% CI, 2.6-3.0), fibroids (aOR, 2.0; 95% CI, 1.8-2.2), preeclampsia (aOR, 3.1; 95% CI, 2.9-3.3), amnionitis (aOR, 2.9; 95% CI, 2.5-3.4), placenta previa or abruption (aOR, 7.0; 95% CI, 6.6-7.3), cervical laceration (aOR, 94.0; 95% CI, 87.3-101.2), uterine rupture (aOR, 11.6; 95% CI, 9.7-13.8), instrumental vaginal delivery (aOR, 1.5; 95% CI, 1.4-1.6), and cesarean delivery (aOR, 1.4; 95% CI, 1.3-1.5). Changes in risk factors, however, accounted for only 5.6% of the increase in severe PPH.

CONCLUSION

A doubling in incidence of severe PPH over 10 years was not explained by contemporaneous changes in studied risk factors.

Hypertensive disorders in twin versus singleton gestations. National Institute of Child Health and Human Development Network of Maternal-Fetal Medicine Units

OBJECTIVE

This study was undertaken to compare rates and severity of gestational hypertension and preeclampsia, as well as perinatal outcomes when these complications develop, between women with twin gestations and those with singleton gestations.

STUDY DESIGN

This was a secondary analysis of prospective data from women with twin (n = 684) and singleton (n = 2946) gestations enrolled in two separate multicenter trials of low-dose aspirin for prevention of preeclampsia. End points were rates of gestational hypertension, rates of preeclampsia, and perinatal outcomes among women with hypertensive disorders.

RESULTS

Women with twin gestations had higher rates of gestational hypertension (relative risk, 2.04; 95% confidence interval, 1.60-2.59) and preeclampsia (relative risk, 2. 62; 95% confidence interval, 2.03-3.38). In addition, women with gestational hypertension during twin gestations had higher rates of preterm delivery at both <37 weeks' gestation (51.1% vs 5.9%; P <. 0001) and <35 weeks' gestation (18.2% vs 1.6%; P <.0001) and also had higher rates of small-for-gestational-age infants (14.8% vs 7. 0%; P =.04). Moreover, when outcomes associated with preeclampsia were compared, women with twin gestations had significantly higher rates of preterm delivery at <37 weeks' gestation (66.7% vs 19.6%; P <.0001), preterm delivery at <35 weeks' gestation (34.5% vs 6.3%; P <.0001), and abruptio placentae (4.7% vs 0.7%; P =.07). In contrast, among women with twin pregnancies, those who remained normotensive had more adverse neonatal outcomes than did those in whom hypertensive complications developed.

CONCLUSIONS

Rates for both gestational hypertension and preeclampsia are significantly higher among women with twin gestations than among those with singleton gestations. Moreover, women with twin pregnancies and hypertensive complications have higher rates of adverse neonatal outcomes than do those with singleton pregnancies.

Effects of smoking during pregnancy. Five meta-analyses

BACKGROUND

The purpose of this study was to estimate, using meta-analysis, pooled odds ratios for the effects of smoking on five pregnancy complications: placenta previa, abruptio placenta, ectopic pregnancy, preterm premature rupture of the membrane (PPROM), and pre-eclampsia.

METHODS

Published articles were identified through computer search and literature review. Five criteria were applied to those studies initially identified to determine those eligible for the meta-analysis. A random effects model was applied to derive pooled odds ratios for the eligible studies for each pregnancy complication. Meta-analyses were repeated on subsets of the studies to confirm the overall results.

RESULTS

Smoking was found to be strongly associated with an elevated risk or placenta previa, abruptio placenta, ectopic pregnancy, and PPROM, and a decreased risk of pre-eclampsia. All pooled odds ratios were statistically significant. The pooled ratios ranged from 1.58 for placenta previa to 1.77 for ectopic pregnancy. The pooled odds ratio for pre-eclampsia was 0.51 and all subset analyses confirmed this seemingly protective effect.

CONCLUSIONS

Smoking during pregnancy is a significant and preventable factor affecting ectopic pregnancy, placental abruption, placenta previa, and PPROM. The findings of smoking's apparently protective effect on pre-eclampsia should be balanced with these harmful effects. In addition, the biological linkage between smoking and pre-eclampsia is not yet well understood. Pregnant women should be advised to stop smoking in order to reduce the overall risk of pregnancy complications as well as any risk of adverse impact on the unborn child.

Treatment for Mild Chronic Hypertension during Pregnancy

BACKGROUND

The benefits and safety of the treatment of mild chronic hypertension (blood pressure, <160/100 mm Hg) during pregnancy are uncertain. Data are needed on whether a strategy of targeting a blood pressure of less than 140/90 mm Hg reduces the incidence of adverse pregnancy outcomes without compromising fetal growth.

METHODS

In this open-label, multicenter, randomized trial, we assigned pregnant women with mild chronic hypertension and singleton fetuses at a gestational age of less than 23 weeks to receive antihypertensive medications recommended for use in pregnancy (active-treatment group) or to receive no such treatment unless severe hypertension (systolic pressure, ≥160 mm Hg; or diastolic pressure, ≥105 mm Hg) developed (control group). The primary outcome was a composite of preeclampsia with severe features, medically indicated preterm birth at less than 35 weeks' gestation, placental abruption, or fetal or neonatal death. The safety outcome was small-for-gestational-age birth weight below the 10th percentile for gestational age. Secondary outcomes included composites of serious neonatal or maternal complications, preeclampsia, and preterm birth.

RESULTS

A total of 2408 women were enrolled in the trial. The incidence of a primary-outcome event was lower in the active-treatment group than in the control group (30.2% vs. 37.0%), for an adjusted risk ratio of 0.82 (95% confidence interval [CI], 0.74 to 0.92; P<0.001). The percentage of small-for-gestational-age birth weights below the 10th percentile was 11.2% in the active-treatment group and 10.4% in the control group (adjusted risk ratio, 1.04; 95% CI, 0.82 to 1.31; P = 0.76). The incidence of serious maternal complications was 2.1% and 2.8%, respectively (risk ratio, 0.75; 95% CI, 0.45 to 1.26), and the incidence of severe neonatal complications was 2.0% and 2.6% (risk ratio, 0.77; 95% CI, 0.45 to 1.30). The incidence of any preeclampsia in the two groups was 24.4% and 31.1%, respectively (risk ratio, 0.79; 95% CI, 0.69 to 0.89), and the incidence of preterm birth was 27.5% and 31.4% (risk ratio, 0.87; 95% CI, 0.77 to 0.99).

CONCLUSIONS

In pregnant women with mild chronic hypertension, a strategy of targeting a blood pressure of less than 140/90 mm Hg was associated with better pregnancy outcomes than a strategy of reserving treatment only for severe hypertension, with no increase in the risk of small-for-gestational-age birth weight. (Funded by the National Heart, Lung, and Blood Institute; CHAP ClinicalTrials.gov number, NCT02299414.).

Etiology and prevention of stillbirth

OBJECTIVE

This is a systematic review of the literature on the causes of stillbirth and clinical opinion regarding strategies for its prevention.

STUDY DESIGN

We reviewed the causes of stillbirth by performing a Medline search limited to articles in English published in core clinical journals from January 1, 1995, to January 1, 2005. Articles before this date were included if they added historical information relevant to the topic. A total of 1445 articles obtained, 113 were the basis of this review and chosen based on the criterion that stillbirth or fetal death was central to the article.

RESULTS

Fifteen risk factors for stillbirths were identified and the prevalence of these conditions and associated risks are presented The most prevalent risk factors for stillbirth are prepregnancy obesity, socioeconomic factors, and advanced maternal age. Biologic markers associated with increased stillbirth risk are also reviewed, and strategies for its prevention identified.

CONCLUSION

Identification of risk factors for stillbirth assists the clinician in performing a risk assessment for each patient. Unexplained stillbirths and stillbirths related to growth restriction are the 2 categories of death that contribute the most to late fetal losses. Late pregnancy is associated with an increasing risk of stillbirth, and clinicians should have a low threshold to evaluate fetal growth. The value of antepartum testing is related to the underlying risk of stillbirth and, although the strategy of antepartum testing in patients with increased risk will decrease the risk of late fetal loss, it is of necessity associated with higher intervention rates.

Maternal-fetal conditions necessitating a medical intervention resulting in preterm birth

OBJECTIVE

The objective of the study was to evaluate the extent to which maternal and fetal conditions necessitate medically indicated preterm birth.

STUDY DESIGN

A population-based, retrospective, cohort study of women who delivered a singleton live birth at 20 weeks or longer in Missouri, 1989 to 1997 was performed (n = 684,711). Maternal-fetal conditions that necessitated iatrogenic preterm birth included preeclampsia, small-for-gestational-age birth, fetal distress, placental abruption, placenta previa, unexplained vaginal bleeding, pregestational and gestational diabetes, renal disease, Rh sensitization, and congenital malformations. We examined the association between each of the aforementioned conditions and risk of medically indicated preterm birth at less than 35 weeks. Medically indicated preterm birth was defined as a labor induction or a prelabor cesarean in the absence of premature rupture of membranes at preterm gestations. Adjusted relative risk with 95% confidence interval for preterm birth was derived from multivariable logistic regression models, and population attributable fractions were calculated.

RESULTS

The preterm birth rate (less than 35 weeks) was 4.6% (n = 31,238), with 23.5% (n = 7,347) of such births being medically indicated. Preeclampsia, fetal distress, small-for-gestational-age, and placental abruption were the most common indications for a medical intervention resulting in preterm birth, with at least 1 of these conditions present in 53.2% of medically indicated preterm births and in 17.7% of term births (relative risk 4.9, 95% confidence interval 4.7, 5.2).

CONCLUSION

Preeclampsia, fetal distress, small-for-gestational-age, and placental abruption, conditions that are associated with ischemic placental disease, are implicated in well over half of all medically indicated preterm births. Although the etiology of preterm birth is heterogeneous, it is reasonable that ischemic placental disease may serve as an important pathway to preterm birth.

Placental abruption and adverse perinatal outcomes

CONTEXT

Pregnancies complicated by abruption result in increased frequency of perinatal death and decreased fetal size and gestational duration, yet the extent of placental separation and its effect on these adverse outcomes is unknown.

OBJECTIVE

To assess the contribution of placental abruption and extent of placental separation to stillbirth, preterm delivery, and fetal growth restriction.

DESIGN

Hospital-based, retrospective cohort study.

SETTING

Mount Sinai Hospital, New York City, NY.

PARTICIPANTS

A total of 53,371 pregnancies occurring in 40,789 women who were delivered of singleton births between 1986 and 1996.

MAIN OUTCOME MEASURES

Risks and relative risks for stillbirth (>20 weeks), preterm delivery (<37 weeks), and fetal growth restriction (birth weight below 10th percentile for gestational age) in relation to abruption.

RESULTS

The incidence of abruption was 1 % (n = 530). Abruption was associated with an 8.9-fold (95% confidence interval [CI], 6.0-13.0) adjusted relative risk (aRR) of stillbirth. Preterm birth proportions among women with and without abruption were 39.6% and 9.1 %, respectively, yielding an aRR of 3.9 (95% CI, 3.5-4.4). In the abruption group, 14.3% of neonates were growth restricted, compared with 8.1 % among all other births (aRR, 2.0; 95% CI, 1.5-2.4). Extent of placental separation had a profound effect on stillbirth (aRR for 75% separation, 31.5; 95% CI, 17.0-58.4), although evident only among those with at least 50% separation. However, the risk of preterm delivery was substantially increased even for mild abruptions (aRR for 25% separation, 5.5; 95% CI, 4.2-7.3).

CONCLUSIONS

In this cohort, placental abruption had a profound impact on stillbirth, preterm delivery, and fetal growth restriction. The risk of stillbirth was dramatically increased for severe placental separation, but preterm delivery was common even among women with lesser degrees of placental separation.

Long-term effects of cesarean sections: ectopic pregnancies and placental problems

OBJECTIVE

Few studies on the long-term effects of cesarean sections exist. The purpose of this study was to investigate the occurrence of three long-term effects, ectopic pregnancy, placenta previa, and abruptio placentae, in the subsequent pregnancy.

STUDY DESIGN

This retrospective cohort study was based on two nationwide registers in Finland: the birth register and the hospital inpatient register. Women (n = 16,938) having had a cesarean section (exposed women) and a matched control group were identified from the birth register. The occurrence and outcome of the first subsequent pregnancy was determined from the 1987 to 1993 hospital inpatient register and the first subsequent birth from the 1987 to 1993 birth register.

RESULTS

During the follow-up time in the hospital inpatient register, fewer exposed women had a completed pregnancy. Ectopic pregnancy was more common among the exposed women than among the controls (risk ratio 1.28). In the first subsequent birth abruptio placentae was more common among primiparous (at index the birth, risk ratios of 3.22 in hospital inpatient register and 2.41 in birth register) and multiparous women (4.52 in hospital inpatient register and 3.89 in birth register). Placenta previa was more common among primiparous exposed women than among control women (risk ratio 5.34 in hospital inpatient register and 3.78 in birth register).

CONCLUSIONS

Cesarean section is a modest risk factor for ectopic pregnancy and an important risk factor for placental problems.

Previous cesarean delivery and risks of placenta previa and placental abruption

OBJECTIVE

To examine the association between cesarean delivery and previa and abruption in subsequent pregnancies.

METHODS

A retrospective cohort study of first 2 (n = 156,475) and first 3 (n = 31,102) consecutive singleton pregnancies using the 1989-1997 Missouri longitudinally linked data were performed. Relative risk (RR) was used to quantify the associations between cesarean delivery and risks of previa and abruption in subsequent pregnancies, after adjusting for several confounders.

RESULTS

Rates of previa and abruption were 4.4 (n = 694) and 7.9 (n = 1,243) per 1,000 births, respectively. The pregnancy after a cesarean delivery was associated with increased risk of previa (0.63%) compared with a vaginal delivery (0.38%, RR 1.5, 95% confidence interval [CI] 1.3-1.8). Cesarean delivery in the first and second births conferred a two-fold increased risk of previa in the third pregnancy (RR 2.0, 95% CI 1.3-3.0) compared with first two vaginal deliveries. Women with a cesarean first birth were more likely to have an abruption in the second pregnancy (0.95%) compared with women who had a vaginal first birth (0.74%, RR 1.3, 95% CI 1.2-1.5). Two consecutive cesarean deliveries were associated with a 30% increased risk of abruption in the third pregnancy (RR 1.3, 95% CI 1.0-1.8). A second pregnancy within a year after a cesarean delivery was associated with increased risks of previa (RR 1.7, 95% CI 0.9-3.1) and abruption (RR 1.5, 95% CI 1.1-2.3).

CONCLUSION

A cesarean first birth is associated with increased risks of previa and abruption in the second pregnancy. There is a dose-response pattern in the risk of previa, with increasing number of prior cesarean deliveries. A short interpregnancy interval is associated with increased risks of previa and abruption.

LEVEL OF EVIDENCE

II-2.

Accuracy of reporting maternal in-hospital diagnoses and intrapartum procedures in Washington State linked birth records

While the impact of maternal morbidities and intrapartum procedures is a common topic in perinatal outcomes research, the accuracy of the reporting of these variables in the large administrative databases (birth certificates, hospital discharges) often utilised for such research is largely unknown. We conducted this study to compare maternal diagnoses and procedures listed on birth certificates, hospital discharge data, and birth certificate and hospital discharge data combined, with those documented in a stratified random sample of hospital medical records of 4541 women delivering liveborn infants in Washington State in 2000. We found that birth certificate and hospital discharge data combined had substantially higher true positive fractions (TPF, proportion of women with a positive medical record assessment who were positive using the administrative databases) than did birth certificate data alone for labour induction (86% vs. 52%), cephalopelvic disproportion (83% vs. 35%), abruptio placentae (85% vs. 68%), and forceps-assisted delivery (89% vs. 55%). For procedures available only in hospital discharge data, TPFs were generally high: episiotomy (85%) and third and fourth degree vaginal lacerations (91%). Except for repeat caesarean section without labour (TPF, 81%), delivery procedures available only in birth certificate data had low TPFs, including augmentation (34%), repeat caesarean section with labour (61%), and vaginal birth after caesarean section (62%). Our data suggest that researchers conducting perinatal epidemiological studies should not rely solely on birth certificate data to detect maternal diagnoses and intrapartum procedures accurately.

Thyroid diseases and adverse pregnancy outcomes in a contemporary US cohort

CONTEXT

Thyroid diseases are inconsistently reported to increase risk for pregnancy complications.

OBJECTIVE

The objective of this study was to study pregnancy complications associated with common and uncommon thyroid diseases.

DESIGN, SETTING, AND PARTICIPANTS

We analyzed singleton pregnancies (N = 223 512) from a retrospective US cohort, the Consortium on Safe Labor (2002-2008). Thyroid diseases and outcomes were derived from electronic medical records. Multivariable logistic regression with generalized estimating equations estimated adjusted odds ratios (ORs) with 99% confidence intervals (99% CI).

MAIN OUTCOME MEASURES

Hypertensive diseases, diabetes, preterm birth, cesarean sections, inductions, and intensive care unit (ICU) admissions were analyzed.

RESULTS

Primary hypothyroidism was associated with increased odds of preeclampsia (OR = 1.47, 99% CI = 1.20-1.81), superimposed preeclampsia (OR = 2.25, 99% CI = 1.53-3.29), gestational diabetes (OR = 1.57, 99% CI = 1.33-1.86), preterm birth (OR = 1.34, 99% CI = 1.17-1.53), induction (OR = 1.15, 99% CI = 1.04-1.28), cesarean section (prelabor, OR = 1.31, 99% CI = 1.11-1.54; after spontaneous labor OR = 1.38, 99% CI = 1.14-1.66), and ICU admission (OR = 2.08, 99% CI = 1.04-4.15). Iatrogenic hypothyroidism was associated with increased odds of placental abruption (OR = 2.89, 99% CI = 1.14-7.36), breech presentation (OR = 2.09, 99% CI = 1.07-4.07), and cesarean section after spontaneous labor (OR = 2.05, 99% CI = 1.01-4.16). Hyperthyroidism was associated with increased odds of preeclampsia (OR = 1.78, 99% CI = 1.08-2.94), superimposed preeclampsia (OR = 3.64, 99% CI = 1.82-7.29), preterm birth (OR = 1.81, 99% CI = 1.32-2.49), induction (OR = 1.40, 99% CI = 1.06-1.86), and ICU admission (OR = 3.70, 99% CI = 1.16-11.80).

CONCLUSIONS

Thyroid diseases were associated with obstetrical, labor, and delivery complications. Although we lacked information on treatment during pregnancy, these nationwide data suggest either that there is a need for better thyroid disease management during pregnancy or that there may be an intrinsic aspect of thyroid disease that causes poor pregnancy outcomes.

Hyperhomocysteinemia: a risk factor for placental abruption or infarction

OBJECTIVE

To establish the prevalence of hyperhomocysteinemia in women with placental abruption or infarction.

DESIGN

Forty-six women with normal pregnancy outcome (controls) and 84 women with placental abruption or infarction (study group) were selected, and studied in the non-pregnant state. Homocysteine metabolism was investigated by a standardized oral methionine loading test. Hyperhomocysteinemia was defined as a concentration of fasting and/or postmethionine plasma homocysteine exceeding the estimated 97.5 percentile level of the controls. In the fasting state, the vitamin status was investigated by the measurement of serum and red cell folate, serum vitamin B12, and whole blood pyridoxal-5'-phosphate (PLP, an active form of vitamin B6).

RESULTS

Hyperhomocysteinemia was diagnosed in four controls (9%) and 26 women of the study group (31%, P < 0.05). The median concentrations of the vitamins studied were significantly lower in women of the study group as compared to the controls, except for red cell folate, where the median concentration was comparable in both groups. The median concentration of fasting plasma homocysteine, unlike post-methionine plasma homocysteine, was significantly higher in women who experienced placental abruption or infarction in their first pregnancy than in women who had the same event after one or more uncomplicated pregnancies.

CONCLUSION

Hyperhomocysteinemia is associated with placental abruption or infarction.

Oral hypoglycaemic agents in 118 diabetic pregnancies

AIMS

To assess maternal and neonatal complications in pregnancies of diabetic women treated with oral hypoglycaemic agents during pregnancy.

METHODS

A cohort study including all consecutively registered, orally treated pregnant diabetic patients set in a diabetic obstetrical service at a university hospital: 50 women treated with metformin, 68 women treated with sulphonylurea during pregnancy and a reference group of 42 diabetic women treated with insulin during pregnancy.

RESULTS

The prevalence of pre-eclampsia was significantly increased in the group of women treated with metformin compared to women treated with sulphonylurea or insulin (32 vs. 7 vs. 10%, P < 0.001). No difference in neonatal morbidity was observed between the orally treated and insulin-treated group; no cases of severe hypoglycaemia or jaundice were seen in the orally treated groups. However, in the group of women treated with metformin in the third trimester, the perinatal mortality was significantly increased compared to women not treated with metformin (11.6 vs. 1.3%, P < 0.02).

CONCLUSION

Treatment with metformin during pregnancy was associated with increased prevalence of pre-eclampsia and a high perinatal mortality.

Preterm birth and maternal smoking: risks related to gestational age and onset of delivery

OBJECTIVE

The object was to examine the effects of smoking on spontaneous and induced very and moderately preterm birth (< or = 32 and 33-36 completed weeks' gestation, respectively).

STUDY DESIGN

Live singleton births in Sweden, 1991-1993 (n = 311,977), were examined.

RESULTS

Risk of preterm birth consistently increased with amount smoked. Smoking was most heavily associated with increased risks of very preterm birth and spontaneous preterm birth. The highest impact of smoking was seen on risk of spontaneous very preterm birth among women who smoked at least 10 cigarettes/d (odds ratio 1.7). The smoking-related risks of preterm birth remained essentially unchanged after excluding pregnancies with smoking-associated pregnancy complications.

CONCLUSIONS

There is a dose-related impact of smoking on risk of preterm birth. The fact that the smoking-related risk of spontaneous preterm birth is more pronounced than that of induced preterm birth suggests that smoking is associated with spontaneous preterm labor.

The clinical significance of uterine leiomyomas in pregnancy

In a retrospective review of 6706 pregnancies between 1981 and 1985, uterine leiomyomas were documented by antenatal sonography in 93 (1.4%) patients. The obstetric records and sonograms of patients with documented leiomyomas were reviewed and compared with data from matched control patients managed at our institution during the same time period. Among the 93 patients with leiomyomas, 14 (15.1%) had one or more leiomyomas subjacent to the maternal surface of the placenta. Significantly, eight of 14 (57%) of these patients with retroplacental leiomyomas subsequently developed abruptio placentae, which resulted in the deaths of four fetuses. Conversely, among the remaining 79 patients whose leiomyomas were not retroplacental, abruptio placentae occurred in only two patients (2.5%), neither of which resulted in fetal death. Clinically significant pain requiring narcotic analgesia developed in 14 of 93 (15.1%) patients and premature labor occurred in 20 of 93 (21.5%); pain and premature labor correlated positively with the size of the largest myoma. Delivery by cesarean section and vacuum assistance occurred significantly more frequently in patients with leiomyomas than in those without documented leiomyomas. In this population uterine myomas did not significantly alter the incidence of intrauterine growth retardation and low Apgar scores.

Cocaine use during pregnancy: perinatal outcomes

The relation between maternal cocaine use and perinatal outcomes was investigated among 17,466 non-Asian singleton deliveries in 1988 from the University of Illinois Perinatal Network data base in the metropolitan Chicago area. Elevated adjusted relative risks (RR) of low birth weight (RR = 2.8, 95% confidence interval (CI) 2.2-3.7), prematurity (RR = 2.4, 95% CI 1.9-3.1), abruptio placentae (RR = 4.5, 95% CI 2.4-8.5), and perinatal death (RR = 2.1, 95% CI 1.1-4.0) were observed for "any" cocaine users (n = 408) compared with women who did not use cocaine or any other drugs or alcohol (n = 17,058). There was an increased (although unstable) risk of intrapartum placenta previa not previously reported (RR = 2.3, 95% CI 1.0-5.1). The relative risk of small-for-gestational-age births for cocaine users who did not smoke (RR = 3.4, 95% CI 1.8-6.5) was greater than that for cocaine users who did (RR = 2.1, 95% CI 1.1-4.1). Irrespective of smoking status, cocaine use during pregnancy increased the risk of small-for-gestational-age births.

Risk factors for adverse maternal outcomes among women with HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome

OBJECTIVE

This study was undertake to determine risk factors for adverse maternal outcomes among women with HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome.

STUDY DESIGN

Maternal medical records of pregnancies complicated by HELLP syndrome managed between July 1, 1992, and April 30, 1999, were reviewed. Risk factors evaluated included maternal age, parity, race, previous preeclampsia, chronic hypertension, gestational age at diagnosis, mean arterial blood pressure, nadir blood platelet count (<50,000 cells/microL vs > or =50,000 cells/microL), and peak serum levels of aspartate aminotransferase and lactate dehydrogenase. Maternal outcome variables analyzed included eclampsia, abruptio placentae, disseminated intravascular coagulopathy, pulmonary edema, pleural effusion, ascites, acute renal failure, liver hematoma, need for transfusion of blood products, cesarean delivery, and death. Statistical analysis was performed with the Student t test, the chi(2) test, and logistic regression analysis.

RESULTS

A total of 183 women with HELLP syndrome were studied. Eclampsia was present in 6%, abruptio placentae was present in 10%, and disseminated intravascular coagulopathy was present in 8%. Forty-one women (22%) required transfusion of blood products. Incidence of eclampsia significantly decreased with increasing gestational age, from 16% at < or =28 weeks' gestation to 3% at >32 weeks' gestation (P <.05) and was higher among African American patients than among white patients (12% vs 3%; P <.05). Logistic regression analysis showed an independent relationship between eclampsia and race (P <.05). Incidence of abruptio placentae was higher among women with previous preeclampsia than among women without this clinical history (26% vs 5%; P <.05). Disseminated intravascular coagulopathy was significantly associated with abruptio placentae (P <.0001) and acute renal failure (P <.0001). A nadir platelet count of <50, 000/microL, a peak serum aspartate aminotransferase level of >150 U/L, and a peak serum lactate dehydrogenase level of >1400 U/L were not independent risk factors for adverse outcome.

CONCLUSIONS

Among women with HELLP syndrome, African American race is a risk factor for eclampsia. Both acute renal failure and abruptio placentae are associated with disseminated intravascular coagulopathy. Laboratory parameters of HELLP syndrome are not independent risk factors for adverse maternal outcome.

Maternal cigarette smoking as a risk factor for placental abruption, placenta previa, and uterine bleeding in pregnancy

The authors carried out an epidemiologic study to evaluate the role of maternal cigarette smoking as a potential risk factor for placental abruption, placenta previa, and uterine bleeding of unknown etiology in pregnancy. Data for this prospective cohort study were obtained from women seeking prenatal care at any of the two tertiary, seven regional, or 17 community hospitals in the province of Nova Scotia, Canada, between January 1, 1986, and December 31, 1993. A total of 87,184 pregnancies (among 61,667 women) were registered in the database. Women who smoked during pregnancy (33%) were compared with nonsmokers, and all women were followed until the termination of pregnancy. Placental abruption was indicated in 9.9 per 1,000 pregnancies, while placenta previa and uterine bleeding of unknown etiology were indicated in 3.6 and 58.9 per 1,000 pregnancies, respectively. Women who smoked had a twofold increase in the risk of abruption (relative risk = 2.05, 95% confidence interval (CI) 1.75-2.40) in comparison with nonsmokers, while the relative risk for placenta previa was 1.36 (95% CI 1.04-1.79). However, cigarette smoking was not found to be associated with uterine bleeding of unknown etiology (relative risk = 1.01, 95% CI 0.94-1.08). There was no evidence for an increased risk of uteroplacental bleeding disorders with increasing numbers of cigarettes smoked. All analyses were adjusted for potentially confounding factors through logistic regression models based on the method of generalized estimating equations. The study confirms a positive association between cigarette smoking and placental abruption and a weak association with placenta previa but not with other uterine bleeding. The distinct pattern of results for placental abruption, placenta previa, and uterine bleeding of unknown origin suggests that these three uteroplacental bleeding disorders do not have a common etiology in relation to cigarette smoking.

Perinatal outcome in women with recurrent preeclampsia compared with women who develop preeclampsia as nulliparas

OBJECTIVE

To compare the rates and perinatal outcome in women who experienced preeclampsia in a previous pregnancy to those in women who developed preeclampsia as nulliparas.

STUDY DESIGN

This is a secondary analysis of data from 2 separate multi-center trials of aspirin for prevention of preeclampsia. Women who had preeclampsia in a previous pregnancy (n = 598) were compared with nulliparous women (n = 2934). Outcome variables were rates of preeclampsia, preterm delivery at <37 and <35 weeks of gestation, small-for-gestational-age infant, abruptio placentae, and perinatal death. Data were compared by using chi-square analysis and Wilcoxon rank sum test.

RESULTS

The rates of preeclampsia and of severe preeclampsia were significantly higher in the previous preeclamptic group as compared to the nulliparous group (17.9% vs 5.3%, P <.0001, and 7.5% vs. 2.4%, P <.0001, respectively). Women who had recurrent preeclampsia experienced more preterm deliveries before 37 and 35 weeks of gestation than nulliparous women who developed preeclampsia. In addition, among women who developed severe preeclampsia, those with recurrent preeclampsia had higher rates of preterm delivery both before 37 weeks (67% vs 33%, P =.0004) and before 35 weeks of gestation (36% vs 19%, P =.041), and higher rates of abruptio placentae (6.7% vs 1.5%) and fetal death (6.7% vs 1.4%) than did nulliparous women.

CONCLUSION

Compared to nulliparous women, women with preeclampsia in a previous pregnancy had significantly higher rates of preeclampsia and adverse perinatal outcomes associated with preterm delivery as a result of preeclampsia.

Risk factors for antepartum and intrapartum stillbirth: a population-based study

To examine disparities in risk factors for stillbirths and its occurrence in the antepartum versus intrapartum periods. A population-based, cross-sectional study using data on women that delivered singleton births between 20 and 43 weeks in Missouri (1989-1997) was conducted (n = 626,883). Hazard ratios and 95% confidence intervals were derived from regression models and population attributable fractions were estimated to examine the impact of risk factors on stillbirth. Among African Americans, risks of antepartum and intrapartum stillbirth were 5.6 and 1.1 per 1,000 singleton births, respectively; risks among whites were 3.4 and 0.5 per 1,000 births, respectively. Maternal age > or = 35 years, lack of prenatal care, prepregnancy body mass index (BMI) > or = 30 kg/m2, and prior preterm or small-for-gestational age birth were significantly associated with increased risk for antepartum stillbirth among whites, but not African Americans. BMI < or = 18.5 kg/m2 was associated with antepartum and intrapartum stillbirth among African Americans, but not whites. The presence of any congenital anomaly, abruption, and cord complications were associated with antepartum stillbirth in both races. Premature rupture of membranes was associated with intrapartum stillbirth among whites and African Americans, but intrapartum fever was associated with intrapartum stillbirth among African Americans. These risk factors were implicated in 54.9% and 19.7% of antepartum and intrapartum stillbirths, respectively, among African American women, and in a respective 46.6% and 11.9% among white women. Considerable heterogeneity in risk factors between antepartum and intrapartum stillbirths is evident. Knowledge on timing of stillbirth specific risk factors may help clinicians in decreasing antepartum and intrapartum stillbirth risks through monitoring and timely intervention.

Review of unexplained infertility and obstetric outcome: a 10 year review

BACKGROUND

Increased maternal and fetal risks have been reported in pregnancies following unexplained infertility. Our aims were to examine the obstetric and perinatal outcome of singleton pregnancies in couples with unexplained infertility and explore the impact of fertility treatment.

METHODS

Women with unexplained infertility were identified from the Aberdeen Fertility Clinic Database. Their unit numbers were matched against the Aberdeen Maternity and Neonatal Databank (AMND) in order to extract obstetric records of those women with subsequent pregnancy outcomes. The general obstetric population served as a control group.

RESULTS

Women with unexplained infertility were older [30.8 versus 27.9 years, 95% confidence interval (CI) for difference = +2.4 to +3.4] and more likely to be primiparous (59 versus 40%, 95% CI = +1.3 to +1.9). After adjusting for age and parity they had a higher incidence of pre-eclampsia, abruptio placentae, preterm labour, emergency Caesarean section and induction of labour in comparison with the general population (P < 0.05). Perinatal outcome did not differ between women with unexplained infertility and those of the general population. The multiple pregnancy rate was 5.4% higher following fertility treatment than in women who conceived spontaneously (95% CI = +2.8 to +9.7).

CONCLUSIONS

Women with unexplained infertility are at higher risk of obstetric complications which persist even after adjusting for age, parity and fertility treatment. The reasons are however unclear and merit further study.

Recurrence of Ischemic Placental Disease

OBJECTIVE

To test the hypothesis that the presence of preeclampsia, small for gestational age (SGA)-birth, and placental abruption in the first pregnancy confers increased risk in the second pregnancy.

METHODS

A retrospective cohort study entailing a case-crossover analysis was performed based on women who had two consecutive singleton live births (n=154,810) between 1989 and 1997 in Missouri. Small for gestational age was defined as infants with birth weight below the 10th centile for gestational age. Risk and recurrence of ischemic placental disease was assessed from fitting logistic regression models after adjusting for several confounders.

RESULTS

Preeclampsia in the first pregnancy was associated with significantly increased risk of preeclampsia (odds ratio 7.03, 95% confidence interval 6.51, 7.59), SGA (odds ratio 1.16, 95% confidence interval 1.06, 1.27), and placental abruption (odds ratio 1.90, 95% confidence interval 1.51, 2.38) in the second pregnancy. Similarly, women with SGA and abruption in the first pregnancy were associated with increased risks of all other conditions in the second pregnancy.

CONCLUSION

Women with preeclampsia, SGA, and placental abruption in their first pregnancy--conditions that constitute ischemic placental disease--are at substantially increased risk of recurrence of any or all these conditions in their second pregnancy. Although causes of these conditions remain largely speculative, these entities may manifest through a common pathway of ischemic placental disease with significant risk of recurrence.

Placental abruption and its association with hypertension and prolonged rupture of membranes: a methodologic review and meta-analysis

OBJECTIVE

To conduct a meta-analysis of published studies on placental abruption to examine its incidence, recurrence, and association with hypertensive disorders (chronic hypertension and preeclampsia) and prolonged rupture of membranes (PROM) in pregnancy.

DATA SOURCES

We reviewed studies on placental abruption published since 1950, based on a comprehensive literature search using MEDLINE, and by identifying studies cited in the references of published reports.

METHODS OF STUDY SELECTION

We identified 54 studies, excluding case reports on placental abruption and studies relating to placenta previa and vaginal bleeding of unknown origin. We also restricted the search to articles published in English.

TABULATION, INTEGRATION, AND RESULTS

Studies chosen for the meta-analysis were categorized based on their study design (case-control or cohort), where they were conducted (United States or other countries), source of the data (vital records versus other sources), and magnitude of risk (risk of abruption greater or less than 1.0%). We used both fixed- and random-effects analysis to identify sources of heterogeneity in results among studies. There were striking differences in the incidence of placental abruption between cohort (0.69%) and case-control (0.35%) studies. United States-based studies found a somewhat higher incidence both for cohort (0.81%) and case-control (0.37%) studies compared with studies conducted outside the U.S. (0.60% and 0.26%, respectively). Abruption was more than ten times more common in pregnancies preceded by a pregnancy with abruption. Chronically hypertensive patients were more than three times as likely to develop placental abruption (odds ratio [OR] 3.13, 95% confidence interval [CI] 2.04-4.80) as normotensive patients. The OR for placental abruption was 1.73 (95% CI 1.47-2.04) for patients with preeclampsia. Similarly, women with pregnancies complicated by PROM were more than three times as likely to develop placental abruption (OR 3.05, 95% CI 2.16-4.32). United States-based studies, case-control studies, and studies with an incidence of abruption greater than 1% demonstrated stronger associations between abruption and hypertension and PROM.

CONCLUSION

Risk of abruption is strongly associated with chronic hypertension, PROM, and especially abruption in a prior pregnancy, and somewhat more modestly with preeclampsia. The criteria for the diagnosis of placental abruption, hypertensive disorders, and PROM may have introduced variability among the results of these studies. More standardized definitions of these pregnancy complications would improve the comparability of the study results.