Richard Dobbie

Gestational Age at Delivery and Special Educational Need: Retrospective Cohort Study of 407,503 Schoolchildren

A retrospective cohort study of 407,503 schoolchildren by Jill Pell and colleagues finds that gestational age at delivery has a dose-dependent relationship with the risk of special educational needs that extends across the full gestational range.

Interpregnancy interval and risk of preterm birth and neonatal death: retrospective cohort study

Abstract Objective To determine whether a short interval between pregnancies is an independent risk factor for adverse obstetric outcome. Design Retrospective cohort study. Setting Scotland. Subjects 89 143 women having second births in 1992-8 who conceived within five years of their first birth. Main outcome measures Intrauterine growth restriction (birth weight less than the 5th centile for gestational age), extremely preterm birth (24-32 weeks), moderately preterm birth (33-36 weeks), and perinatal death. Results Women whose subsequent interpregnancy interval was less than six months were more likely than other women to have had a first birth complicated by intrauterine growth restriction (odds ratio 1.3, 95% confidence interval 1.1 to 1.5), extremely preterm birth (4.1, 3.2 to 5.3), moderately preterm birth (1.5, 1.3 to 1.7), or perinatal death (24.4, 18.9 to 31.5). They were also shorter, less likely to be married, and more likely to be aged less than 20 years at the time of the second birth, to smoke, and to live in an area of high socioeconomic deprivation. When the outcome of the second birth was analysed in relation to the preceding interpregnancy interval and the analysis confined to women whose first birth was a term live birth (n = 69 055), no significant association occurred (adjusted for age, marital status, height, socioeconomic deprivation, smoking, previous birth weight vigesimal, and previous caesarean delivery) between interpregnancy interval and intrauterine growth restriction or stillbirth. However, a short interpregnancy interval (< 6 months) was an independent risk factor for extremely preterm birth (adjusted odds ratio 2.2, 1.3 to 3.6), moderately preterm birth (1.6, 1.3 to 2.0), and neonatal death unrelated to congenital abnormality (3.6, 1.2 to 10.7). The adjusted attributable fractions for these associations were 6.1%, 3.9%, and 13.8%. The associations were very similar when the analysis was confined to married non-smokers aged 25 and above. Conclusions A short interpregnancy interval is an independent risk factor for preterm delivery and neonatal death in the second birth.

Maternal Obesity in Early Pregnancy and Risk of Spontaneous and Elective Preterm Deliveries: A Retrospective Cohort Study

Objectives. We sought to determine the association between maternal body mass index and risk of preterm delivery.Methods. We assessed 187 290 women in Scotland and estimated adjusted odds ratios for spontaneous and elective preterm deliveries among overweight, obese, and morbidly obese women relative to normal-weight women.Results. Among nulliparous women, the risk of requiring an elective preterm delivery increased with increasing BMI, whereas the risk of spontaneous preterm labor decreased. Morbidly obese nulliparous women were at increased risk of all-cause preterm deliveries, neonatal death, and delivery of an infant weighing less than 1000 g who survived to 1 year of age (a proxy for severe long-term disability). By contrast, obesity and elective preterm delivery were only weakly associated among multiparous women.Conclusions. Obese nulliparous women are at increased risk of elective preterm deliveries. This in turn leads to an increased risk of perinatal mortality and is likely to lead to increased ...

Circulating angiogenic factors in early pregnancy and the risk of preeclampsia, intrauterine growth restriction, spontaneous preterm birth, and stillbirth

OBJECTIVE: To estimate the relationship between maternal serum levels of placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) in early pregnancy with the risk of subsequent adverse outcome. METHODS: A nested, case–control study was performed within a prospective cohort study of Down syndrome screening. Maternal serum levels of sFlt-1 and PlGF at 10–14 weeks of gestation were compared between 939 women with complicated pregnancies and 937 controls. Associations were quantified as the odds ratio for a one decile increase in the corrected level of the analyte. RESULTS: Higher levels of sFlt-1 were not associated with the risk of preeclampsia but were associated with a reduced risk of delivery of a small for gestational age infant (odds ratio [OR] 0.92, 95% confidence interval [CI] 0.88–0.96), extreme (24–32 weeks) spontaneous preterm birth (OR 0.90, 95% CI 0.83–0.99), moderate (33–36 weeks) spontaneous preterm birth (OR 0.93, 95% CI 0.88–0.98), and stillbirth associated with abruption or growth restriction (OR 0.77, 95% CI 0.61–0.95). Higher levels of PlGF were associated with a reduced risk of preeclampsia (OR 0.95, 95% CI 0.90–0.99) and delivery of a small for gestational age infant (OR 0.95, 95% CI 0.91–0.99). Associations were minimally affected by adjustment for maternal characteristics. CONCLUSION: Higher early pregnancy levels of sFlt-1 and PlGF were associated with a decreased risk of adverse perinatal outcome. LEVEL OF EVIDENCE: II

Mode of delivery and the risk of delivery-related perinatal death among twins at term: a retrospective cohort study of 8073 births

Objective  To determine the risk of perinatal death among twins born at term in relation to mode of delivery.

Pregnancy-associated plasma protein A and alpha-fetoprotein and prediction of adverse perinatal outcome.

OBJECTIVE: To describe the association between pregnancy associated plasma protein A (PAPP-A), alpha-fetoprotein (AFP) and adverse perinatal outcome. METHODS: We conducted a multicenter prospective cohort study of 8,483 women attending for prenatal care in southern Scotland between 1998 and 2000. The risk of delivering a small for gestational age infant, delivering preterm, and stillbirth were related to maternal serum levels of PAPP-A and AFP. RESULTS: Women with a low PAPP-A were not more likely to have elevated levels of AFP. Compared with women with a normal PAPP-A and a normal AFP, the odds ratio for delivering a small for gestational age infant for women with a high AFP was 0.9 (95% confidence interval [CI] 0.5–1.6), for women with a low PAPP-A was 2.8 (95% CI 2.0–4.0), and for women with both a high AFP and a low PAPP-A was 8.5 (95% CI 3.6–20.0). The odds ratio for delivering preterm for women with a high AFP was 1.8 (95% CI 1.3–2.7), for women with a low PAPP-A was 1.9 (95% CI 1.3–2.7), and for women with both a low PAPP-A and a high AFP was 9.9 (95% CI 4.4–22.0). These interactions were statistically significant for both outcomes (P = .03 and .04, respectively). There was a nonsignificant trend toward a similar interaction in relation to stillbirth risk. Of the women with the combination of a low PAPP-A and high AFP, 32.1% (95% CI 15.9–52.4) delivered a low birth weight infant. CONCLUSION: Low maternal serum levels of PAPP-A between 10 and 14 weeks and high levels of AFP between 15 and 21 weeks gestation are synergistically associated with adverse perinatal outcome. LEVEL OF EVIDENCE: II-2

Factors predisposing to perinatal death related to uterine rupture during attempted vaginal birth after caesarean section: retrospective cohort study

Abstract Objective To determine the factors associated with an increased risk of perinatal death related to uterine rupture during attempted vaginal birth after caesarean section. Design Population based retrospective cohort study. Setting Data from the linked Scottish Morbidity Record and Stillbirth and Infant Death Survey of births in Scotland, 1985-98. Participants All women with one previous caesarean delivery who gave birth to a singleton infant at term by a means other than planned repeat caesarean section (n = 35 854). Main outcome measures All intrapartum uterine rupture and uterine rupture resulting in perinatal death (that is, death of the fetus or neonate). Results The overall proportion of vaginal births was 74.2% and of uterine rupture was 0.35%. The risk of intrapartum uterine rupture was higher among women who had not previously given birth vaginally (adjusted odds ratio 2.5, 95% confidence interval 1.6 to 3.9, P < 0.001) and those whose labour was induced with prostaglandin (2.9, 2.0 to 4.3, P < 0.001). Both factors were also associated with an increased risk of perinatal death due to uterine rupture. Delivery in a hospital with < 3000 births a year did not increase the overall risk of uterine rupture (1.1, 0.8 to 1.5, P = 0.67). However, the risk of perinatal death due to uterine rupture was significantly higher in hospitals with < 3000 births a year (one per 1300 births) than in hospitals with ≥ 3000 births a year (one per 4700; 3.4, 1.0 to 14.3, P = 0.04). Conclusion Women who have not previously given birth vaginally and those whose labour is induced with prostaglandin are at increased risk of uterine rupture when attempting vaginal birth after caesarean section. The risk of consequent death of the infant is higher in units with lower annual numbers of births.

Predicting Cesarean Section and Uterine Rupture among Women Attempting Vaginal Birth after Prior Cesarean Section

Background There is currently no validated method for antepartum prediction of the risk of failed vaginal birth after cesarean section and no information on the relationship between the risk of emergency cesarean delivery and the risk of uterine rupture. Methods and Findings We linked a national maternity hospital discharge database and a national registry of perinatal deaths. We studied 23,286 women with one prior cesarean delivery who attempted vaginal birth at or after 40-wk gestation. The population was randomly split into model development and validation groups. The factors associated with emergency cesarean section were maternal age (adjusted odds ratio [OR] = 1.22 per 5-y increase, 95% confidence interval [CI]: 1.16 to 1.28), maternal height (adjusted OR = 0.75 per 5-cm increase, 95% CI: 0.73 to 0.78), male fetus (adjusted OR = 1.18, 95% CI: 1.08 to 1.29), no previous vaginal birth (adjusted OR = 5.08, 95% CI: 4.52 to 5.72), prostaglandin induction of labor (adjusted OR = 1.42, 95% CI: 1.26 to 1.60), and birth at 41-wk (adjusted OR = 1.30, 95% CI: 1.18 to 1.42) or 42-wk (adjusted OR = 1.38, 95% CI: 1.17 to 1.62) gestation compared with 40-wk. In the validation group, 36% of the women had a low predicted risk of caesarean section (<20%) and 16.5% of women had a high predicted risk (>40%); 10.9% and 47.7% of these women, respectively, actually had deliveries by caesarean section. The predicted risk of caesarean section was also associated with the risk of all uterine rupture (OR for a 5% increase in predicted risk = 1.22, 95% CI: 1.14 to 1.31) and uterine rupture associated with perinatal death (OR for a 5% increase in predicted risk = 1.32, 95% CI: 1.02 to 1.73). The observed incidence of uterine rupture was 2.0 per 1,000 among women at low risk of cesarean section and 9.1 per 1,000 among those at high risk (relative risk = 4.5, 95% CI: 2.6 to 8.1). We present the model in a simple-to-use format. Conclusions We present, to our knowledge, the first validated model for antepartum prediction of the risk of failed vaginal birth after prior cesarean section. Women at increased risk of emergency caesarean section are also at increased risk of uterine rupture, including catastrophic rupture leading to perinatal death.

Neonatal respiratory morbidity at term and the risk of childhood asthma

Objective: To determine whether neonatal respiratory morbidity at term is associated with an increased risk of later asthma and whether this may explain previously described associations between caesarean delivery and asthma. Design: Retrospective cohort study using Scottish Morbidity Record (SMR) data of maternity (SMR02), neonatal (SMR11), and acute hospital (SMR01) discharges. Setting: Scotland. Participants: All singleton births at term between 1992–1995 in 23 Scottish maternity hospitals. Main outcome measures: Hospital admission with a diagnosis of asthma in the principal position between 1992 and 2000. Results: Children who had a diagnosis of transient tachypnoea of the newborn or respiratory distress syndrome were at increased risk of being admitted to hospital with a diagnosis of asthma (hazard ratio (HR) 1.7, 95% confidence interval (95% CI) 1.4 to 2.2, p<0.001). This association was observed both among children delivered vaginally (HR 1.5, 95% CI 1.1 to 2.0, p = 0.007) and among those delivered by caesarean section (HR 2.2, 95% CI 1.6 to 3.0, p<0.001). In the absence of neonatal respiratory morbidity, delivery by caesarean section was weakly associated with the risk of asthma in childhood (HR 1.1, 95% CI 1.0 to 1.2, p = 0.004). The strengths of the associations were similar whether the caesarean delivery was planned or emergency and were not significantly altered by adjustment for maternal, obstetric, and other neonatal characteristics. Conclusions: Neonatal respiratory morbidity at term is associated with an increased risk of asthma in childhood which may explain previously described associations between caesarean delivery and later asthma.

Maternal and biochemical predictors of antepartum stillbirth among nulliparous women in relation to gestational age of fetal death

Objective  To determine whether maternal serum levels of alphafetoprotein (α‐FP) and human chorionic gonadotrophin (hCG) at 15–21 weeks provided clinically useful prediction of stillbirth in first pregnancies.