Discussion: 'vitamin D deficiency in pregnancy and gestational diabetes,' by Burris et al.

In the roundtable that follows, clinicians discuss a study published in this issue of the Journal in light of its methodology, relevance to practice, and implications for future research. Article discussed: Burris HH, Rifas-Shiman SL, Kleinman K, et al. Vitamin D deficiency in pregnancy and gestational diabetes. Am J Obstet Gynecol 2012;207:182.e1-8.

The effects of obesity on the first stage of labor.

OBJECTIVE: To estimate the effects of obesity on the duration and progression of the first stage of labor in a predominantly obese population and estimate the dose-effect with increasing classes of obesity. METHODS: We performed a retrospective cohort study of labor progression among 5,204 consecutive parturients with singleton term pregnancies (37 weeks of gestation or more) and vertex presentation who completed the first stage of labor. Two comparison groups were defined by body mass index (BMI) less than 30 (n=2,413) or 30 or more (n=2,791). Repeated-measures analysis with polynomial modeling was used to construct labor curves. The duration and progression among women with BMIs less than 30 and BMIs of 30 or more were compared in a multivariable interval-censored regression model adjusting for parity, type of labor onset, race, and birth weight more than 4,000 g. RESULTS: The labor curves indicate longer duration and slower progression of the first stage of labor among women with BMIs of 30 or more for both nulliparous and multiparous women. Multivariable interval-censored regression analysis confirmed significantly longer duration (4-10 cm: 4.7 compared with 4.1 hours, P<.01) and slower progression of cervical dilation from 4 to 6 cm (2.2 compared with 1.9 hours, P<.01 with a range of 0.5-10.0 hours) among women with BMIs of 30 or more after adjusting for confounders. CONCLUSION: The overall duration is longer and progression of the early part of the first stage of labor is slower in obese women. This suggests that obesity should be considered in defining norms for management of labor, particularly in the early part of the first stage.

Neural tube defects and associated low birth weight.

OBJECTIVE: To estimate the association between neural tube defects (NTDs) and low birth weight. STUDY DESIGN: This was a retrospective cohort study of women undergoing ultrasound from 17 to 22 weeks from 1990 to 2008. Presence or absence of fetal NTD defined the two study groups. The primary outcomes were intrauterine growth restriction (IUGR), birth weight <10th percentile, and severe IUGR <5th percentile. Subgroup analysis was performed to observe if the association with IUGR persisted. RESULTS: Of 66,956 women, 170 were found to have fetal NTD. Only the rate of advanced maternal age differed between the study groups. Fetuses with an NTD were at significantly increased risk for IUGR <10th percentile (adjusted odds ratio [aOR] 2.6, 95% confidence interval [CI] 1.8 to 3.9) and <5th percentile (aOR 2.8, 95% CI 1.9 to 4.3). The association persisted in subgroup analyses. CONCLUSION: Fetuses with NTD are at increased risk for IUGR, suggesting that a policy of serial growth scans in cases with isolated NTD is justified.

Discussion: 'placental dysfunction disorders across generations' by Wikström et al.

In the roundtable that follows, clinicians discuss a study published in this issue of the Journal in light of its methodology, relevance to practice, and implications for future research. Article discussed: Wikström A-K, Svensson T, Kieler H, et al. Recurrence of placental dysfunction disorders across generations. Am J Obstet Gynecol 2011;205:454.e1-8.

Perinatal outcomes in women with subchorionic hematoma: a systematic review and meta-analysis.

OBJECTIVE: To estimate the association between subchorionic hematoma and adverse perinatal outcomes. DATA SOURCES: MEDLINE, EMBASE, and the Cochrane Library. METHODS OF STUDY SELECTION: We searched English language publications from January 1981 to August 2010 for cohort and case-control studies evaluating subchorionic hematoma and perinatal outcomes. The primary outcome was pregnancy loss (spontaneous abortion and stillbirth). Secondary outcomes were abruption, preterm premature rupture of membranes, preterm delivery, pre-eclampsia, and small for gestational age. Pooled odds ratios (ORs) were calculated from random effects models. TABULATION, INTEGRATION, RESULTS: Seven studies including 1,735 women with subchorionic hematoma and 70,703 controls met inclusion criteria. Subchorionic hematoma was associated with an increased risk of spontaneous abortion (from 8.9% to 17.6%; pooled OR 2.18, 95% confidence interval [CI] 1.29-3.68) and stillbirth (from 0.9% to 1.9%, pooled OR 2.09, 95% CI 1.20-3.67). The number needed to harm was 11 for spontaneous abortion and 103 for stillbirth, meaning one extra spontaneous abortion is estimated to occur for every 11 women with subchorionic hematoma diagnosed and one extra stillbirth occurs for every 103 women with subchorionic hematoma diagnosed. Women with subchorionic hematoma were also at increased risk of abruption (from 0.7% to 3.6%, pooled OR 5.71, 95% CI 3.91-8.33), preterm delivery (from 10.1% to 13.6%, pooled OR 1.40, 95% CI 1.18-1.68), and preterm premature rupture of membranes (from 2.3% to 3.8%, pooled OR 1.64, 95% CI 1.22-2.21), but not small for gestational age (OR 1.69, 95% CI 0.89-3.19) or pre-eclampsia (OR 1.47, 95% CI 0.37-5.89). The numbers needed to harm were 34, 28, and 69 for abruption, preterm delivery, and preterm premature rupture of membranes, respectively. CONCLUSION: Subchorionic hematoma is associated with an increased risk of early and late pregnancy loss, abruption, and preterm premature rupture of membranes.

Ultrasound-detected subchorionic hemorrhage and the obstetric implications.

OBJECTIVE: To estimate the association between the ultrasonographic diagnosis of subchorionic hemorrhage and adverse pregnancy outcomes. METHODS: This was a retrospective cohort study of all consecutive women undergoing routine ultrasonography before 22 weeks with a singleton gestation at one institution from 1994 to 2008. Presence or absence of subchorionic hemorrhage defined the two study groups. The primary outcomes were abruption, intrauterine growth restriction defined as birth weight less than the 10th percentile, and nonanomalous intrauterine fetal demise after 20 weeks. Secondary outcomes included preeclampsia, preterm premature rupture of membranes, and preterm delivery before 37 weeks and before 34 weeks of gestation. Univariable, bivariate, and multiple logistic regression analyses were performed. RESULTS: Of the 63,966 women in the patient population, 1,081 had subchorionic hemorrhage (1.7%). Women with a subchorionic hemorrhage were at increased risk of abruption (n=432, 3.6% compared with 0.6%, adjusted odds ratio 2.6, 95% confidence interval 1.8-3.7) and of preterm delivery (n=6,601, 15.5% compared with 10.5%, adjusted odds ratio 1.3, 95% confidence interval 1.1-1.5), even after adjusting for bleeding during pregnancy, chronic hypertension, body mass index, race, diabetes mellitus, tobacco use, and previous preterm delivery. CONCLUSION: Women with ultrasound-detected subchorionic hemorrhage before 22 weeks of gestation are at increased risk of placental abruption and preterm delivery but are not at increased risk of other adverse pregnancy outcomes. LEVEL OF EVIDENCE: II.