Amanda Trudell

Risk of stillbirth after 37 weeks in pregnancies complicated by small-for-gestational-age fetuses

OBJECTIVE The evidence for delivering small-for-gestational-age (SGA) fetuses at 37 weeks remains conflicting. We examined the risk of stillbirth per week of gestation beyond 37 weeks for pregnancies complicated by SGA. STUDY DESIGN Singleton pregnancies undergoing routine second trimester ultrasound from 1990-2009 were examined retrospectively. The risk of stillbirth per 10,000 ongoing SGA pregnancies with 95% confidence intervals (CIs) was calculated for each week of gestation ≥37 weeks. Using a life-table analysis with correction for censoring, conditional risks of stillbirth, cumulative risks of stillbirth per 10,000 ongoing SGA pregnancies and relative risks (RRs) were calculated with 95% CIs for each week of gestation. RESULTS Among 57,195 pregnancies meeting inclusion criteria the background risk of stillbirth was 56/10,000 (95% CI, 42.3-72.7) with stillbirth risk for SGA pregnancies of 251/10,000 (95% CI, 221.2-284.5). The risk of stillbirth after the 37th week was greater compared with pregnancies delivered in the 37th week (47/10,000, 95% CI, 34.6-62.5 vs 21/10,000, 95% CI, 13.0-32.1; RR, 2.2; 95% CI, 1.3-3.7). The cumulative risk of stillbirth rose from 28/10,000 ongoing SGA pregnancies at 37 weeks to 77/10,000 at 39 weeks (RR, 2.75; 95% CI, 1.79-4.2). Among pregnancies complicated by SGA <5% the cumulative risk of stillbirth at 38 weeks was significantly greater than the risk at 37 weeks (RR, 2.3; 95% CI, 1.4-3.8). CONCLUSION There is a significantly increased risk of stillbirth in pregnancies complicated by SGA delivered after the 37th week. Given these findings, we advocate a policy of delivery of SGA pregnancies 37-38 weeks.

Diagnosis of spina bifida on ultrasound: Always termination?

Open spina bifida is a non-lethal fetal anomaly. Significant advances in the prevention, diagnosis and treatment of open spina bifida have been made over the past 75 years. The most significant strategy for the prevention of open spina bifida has been with folic acid supplementation; however, further investigation into the complicated role that genetics and the environment play in metabolism are coming to light. Ultrasound is the gold standard diagnostic tool for spina bifida. Three-dimensional ultrasound and magnetic resonance imaging are also beginning to play a role in the characterisation of the open spina bifida spinal lesion. Lesion level has been closely correlated to short and long-term outcomes, and prenatal characterisation of lesion level on ultrasound is important for patient counselling. Long-term outcomes of people living with spina bifida are available and should be used for non-directive patient counselling about pregnancy choices for women with open spina bifida.

Stillbirth and the small fetus: use of a sex-specific versus a non-sex-specific growth standard

Objective:To determine if the use of a sex-specific standard to define small-for-gestational age (SGA) will improve prediction of stillbirth.Study design:We performed a retrospective cohort study of singleton pregnancies excluding anomalies, aneuploidy, undocumented fetal sex or birthweight. SGA was defined as birthweight <10th percentile by the non-sex-specific and sex-specific Alexander standards. The association between SGA and stillbirth using these standards was assessed using logistic regression.Result:Among 57 170 pregnancies meeting inclusion criteria, 319 (0.6%) pregnancies were complicated by stillbirth. The area under the receiver operating characteristic curve for the prediction of stillbirth was greater for the sex-specific compared to the non-sex-specific standard (0.83 vs 0.72, P<0.001).Conclusion:Our findings suggest adoption of a sex-specific standard for diagnosis of SGA as it is more discriminative in identifying the SGA fetus at risk for stillbirth.

Balancing the risks of stillbirth and neonatal death in the early preterm small-for-gestational-age fetus

OBJECTIVE Timing of delivery for the early preterm small-for-gestational-age (SGA) fetus remains unknown. Our aim was to estimate the risk of stillbirth in the early preterm SGA fetus compared with the risk of neonatal death. STUDY DESIGN We performed a retrospective cohort study of singleton pregnancies that underwent second-trimester anatomy ultrasound (excluding fetal anomalies, aneuploidy, and pregnancies with incomplete neonatal follow-up data). SGA was defined as birthweight <10th percentile by the Alexander standard. Life-table analysis was used to calculate the cumulative risks of stillbirth per 10,000 ongoing SGA pregnancies and of neonatal death per 10,000 SGA live births for 2-week gestational age strata in the early preterm period (24-33 weeks 6 days of gestation). We further examined the composite risk of expectant management and then compared the risk of expectant management with the risk of immediate delivery. RESULTS Of 76,453 singleton pregnancies, 7036 SGA pregnancies that met inclusion criteria were ongoing at 24 weeks of gestation; there were 64 stillbirths, 226 live births, and 18 neonatal deaths from 24-33 weeks 6 days of gestation. As the risk of stillbirth increases with advancing gestational age, the risk of neonatal death falls, until the 32-33 weeks 6 days of gestation stratum. The relative risk of expectant management compared with immediate delivery remains <1 for each gestational age strata. CONCLUSION Our findings suggest that the balance between the competing risks of stillbirth and neonatal death for the early preterm SGA fetus occurs at 32-33 weeks 6 days of gestation. These data can be useful when delivery timing remains uncertain.

A stillbirth calculator: Development and internal validation of a clinical prediction model to quantify stillbirth risk

Objective To generate a clinical prediction tool for stillbirth that combines maternal risk factors to provide an evidence based approach for the identification of women who will benefit most from antenatal testing for stillbirth prevention. Design Retrospective cohort study Setting Midwestern United States quaternary referral center Population Singleton pregnancies undergoing second trimester anatomic survey from 1999–2009. Pregnancies with incomplete follow-up were excluded. Methods Candidate predictors were identified from the literature and univariate analysis. Backward stepwise logistic regression with statistical comparison of model discrimination, calibration and clinical performance was used to generate final models for the prediction of stillbirth. Internal validation was performed using bootstrapping with 1,000 repetitions. A stillbirth risk calculator and stillbirth risk score were developed for the prediction of stillbirth at or beyond 32 weeks excluding fetal anomalies and aneuploidy. Statistical and clinical cut-points were identified and the tools compared using the Integrated Discrimination Improvement. Main outcome measures Antepartum stillbirth Results 64,173 women met inclusion criteria. The final stillbirth risk calculator and score included maternal age, black race, nulliparity, body mass index, smoking, chronic hypertension and pre-gestational diabetes. The stillbirth calculator and simple risk score demonstrated modest discrimination but clinically significant performance with no difference in overall performance between the tools [(AUC 0.66 95% CI 0.60–0.72) and (AUC 0.64 95% CI 0.58–0.70), (p = 0.25)]. Conclusion A stillbirth risk score was developed incorporating maternal risk factors easily ascertained during prenatal care to determine an individual woman’s risk for stillbirth and provide an evidenced based approach to the initiation of antenatal testing for the prediction and prevention of stillbirth.

Large for gestational age and stillbirth: Is there a role for antenatal testing?: LGA and stillbirth risk

To investigate the association between large‐for‐gestational‐age (LGA) pregnancy and stillbirth to determine if the LGA fetus may benefit from antenatal testing with non‐stress test or biophysical profile.

Use of a simple clinical tool for airway assessment to predict adverse pregnancy outcomes.

OBJECTIVE Obstructive sleep apnea (OSA) is a risk factor for adverse perinatal outcomes. We aimed to test the hypothesis that maternal Mallampati class (MC), as a marker for OSA, is associated with adverse perinatal outcomes. STUDY DESIGN We performed a retrospective secondary analysis of a prospective cohort of term births (≥ 37 weeks). Fetal anomalies and aneuploidy were excluded. Primary outcome was small for gestational age (SGA). Secondary outcomes included preeclampsia, neonatal cord arterial blood gas pH < 7.10 and < 7.05, base excess <  - 8 and <  - 12 mEq/L. Outcomes were compared between mothers with low MC airways and high MC airways using logistic regression. RESULTS A total of 1,823 women met the inclusion criteria. No significant differences were found in the risk of SGA (adjusted odds ratio [aOR] 0.9, 95% confidence interval [CI] 0.6-1.2), preeclampsia (aOR 1.2, 95% CI 0.8-1.9) or neonatal acidemia (aOR 0.8, 95% CI 0.3-2.0), between high and low MC. CONCLUSION High MC is not associated with adverse perinatal outcomes.

Discussion: ‘Sleep-disordered breathing and adverse pregnancy outcomes’ by Pamidi 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.

Discussion: ‘Time from consent to cesarean delivery,’ by Salmeen 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: Salmeen K, Brincat C. Time from consent to cesarean delivery during labor. Am J Obstet Gynecol 2013;209:212.e1-6.