Relation between perinatal outcome and gestational duration in term primiparous pregnancies stratified by body mass index.

INTRODUCTION: There is growing evidence that induction of labor at 41 completed weeks improves neonatal outcome, at least among primiparous women. This study was performed to investigate whether maternal body mass index (BMI) should be considered when deciding on timing of intervention in term pregnancies. MATERIAL AND METHODS: The study design was a historical cohort study using data from the Swedish Medical Birth Register, singletons in cephalic presentation with births 39+0 to 41+6 weeks, with available information on maternal BMI 2005-2017 (n = 352 567). Modified Poisson regression analyses were used to investigate the association between gestational duration and stillbirth or death before 45 postmenstrual weeks (primary outcome) and Apgar score <7 at 5 minutes (secondary outcome) by BMI, respectively. Adjustments were made for maternal age, smoking, country of birth and educational level. RESULTS: The adjusted relative risk (ARR) of stillbirth or death before 45 weeks among infants born at 41+0 to 41+6 vs 40+0 to 40+6 weeks, was 1.26 with a 95% confidence interval (CI) of 1.07-1.48. Among women with BMI ≥30, the offspring mortality risk in pregnancies lasting 39+0 to 39+2 weeks was significantly above the corresponding risk among women of normal BMI who delivered at 41+0 to 41+2 weeks (ARR = 1.95; 95% CI 1.07-3.56) but no statistically significant heterogeneity was found regarding the magnitude of the association between gestational duration and offspring mortality. The ARR, for Apgar <7 at 5 minutes (41+0 to 41+6 vs 40+0 to 40+6 weeks, regardless of BMI), was 1.36 (95% CI 1.27-1.45). The risk for low Apgar score at 41+0 weeks was 1.5% among all children regardless of maternal BMI. Among children to women with BMI ≥30, this magnitude of risk was found already at 39+3 weeks. CONCLUSIONS: In primiparous women with obesity the risk of stillbirth or death before 45 postmenstrual weeks were increased throughout all full-term gestational age categories, compared with women with overweight or normal BMI. Children to obese women had the same risk for Apgar scores <7 at 5 minutes compared with women overall at earlier gestational age. The results suggest that maternal BMI needs to be considered when discussing timing of elective induction in term healthy pregnancies of primiparous women.

Retrospective study of maternal and neonatal outcomes after induction compared to spontaneous start of labour in women with one previous birth in uncomplicated pregnancies ≥ 41+3.

OBJECTIVES: To study the association between induction and outcome among two-parous women in uncomplicated pregnancies ≥ 41+3, stratified by first labour delivery mode and conditions present at first delivery. METHODS: The Swedish Medical Birth Register was used to identify 58,964 uncomplicated singleton pregnancies among women with one previous birth between 1998 and 2014. Women with any registered pregnancy complications were excluded to minimise the risk for indication bias. The outcomes considered were emergency caesarean section (CS), and poor neonatal outcome (Apgar score <7 at 5 min, neonatal death, or meconium aspiration). RESULTS: Women who were induced at their second labour had higher emergency CS rates compared to women in spontaneously started deliveries (adjusted risk ratio, ARR: 2.11; 95% CI: 2.00-2.23). Low Apgar score was more common after induction compared to spontaneously started labours (1.0 vs. 0.7%) (ARR: 1.44; 95% CI: 1.18-1.77). Increased CS rates were also found when comparing induction at 41 + 3 to 41 + 6 weeks to labour at 42 weeks or more, regardless of labour start (ARR 1.39; 95% CI: 1.26-1.52). CONCLUSIONS: We found an increased risk of CS and poor neonatal outcome after second labour induction in prolonged pregnancies. The second labour vaginal success rate after induction was highly dependent, on first labour delivery mode, but also on diagnoses and conditions present at the first delivery.

Improved neonatal outcome after active management of prolonged pregnancies beyond 41+2 weeks in nulliparous, but not among multiparous women.

INTRODUCTION: Prolonged pregnancies are associated with adverse maternal and fetal outcome. In Sweden, no national guidelines exist for when to induce prolonged pregnancies. MATERIAL AND METHODS: Singleton cephalic prolonged pregnancies (defined as ≥ 41+3 gestational weeks) during 2001-2013 (n = 199 770) were identified using the Swedish Medical Birth Register. The maternity units were divided into three groups (tertiles) based on the proportion of pregnancies ≥ 42+3 gestational weeks among all pregnancies ≥ 41+3  weeks. The pregnancy outcome among women delivered at the units with the most expectant management of prolonged pregnancies (> 17.6% proceeding to 42+3  weeks), was compared with that among women delivered at units with the most active management (< 12.6% proceeding to 42+3  weeks). Odds ratios (OR) were calculated using simple and multiple logistic regression. Adjustments were made for year of delivery, hospital level, maternal age, body mass index, and smoking. RESULTS: Among primiparas, an increased risk of Apgar score < 7 at 5 minutes [odds ratio (OR) 1.27, 95% CI 1.16-1.41] and meconium aspiration (OR 1.49, 95% CI 1.14-1.95) was found after birth at most expectant units compared with most active units, but among multiparas, no such associations were detected. A decreased rate of cesarean section was found for both primiparas (OR 0.83, 95% CI 0.80-0.86) and multiparas (OR 0.82, 95% CI 0.77-0.86) at units with expectant vs. active management. No association between perinatal death and delivery-unit specific management of prolonged pregnancies was detected. CONCLUSIONS: Offspring to primiparas might gain from a more active management of prolonged pregnancies, whereas no such improvement of neonatal outcome among multiparous women was detected.