Pre-pregnant body mass index, gestational weight gain and the risk of operative delivery

Authors

  • Nils-Halvdan Morken,

    Corresponding author
    1. Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway
    • Department of Public Health and Primary Health Care, University of Bergen, Bergen, Norway
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  • Kari Klungsøyr,

    1. Department of Public Health and Primary Health Care, University of Bergen, Bergen, Norway
    2. Medical Birth Registry of Norway, Norwegian Institute of Public Health, Bergen, Norway
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  • Per Magnus,

    1. Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway
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  • Rolv Skjærven

    1. Department of Public Health and Primary Health Care, University of Bergen, Bergen, Norway
    2. Medical Birth Registry of Norway, Norwegian Institute of Public Health, Bergen, Norway
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  • The authors have stated explicitly that there are no conflicts of interest in connection with this article.

Correspondence

Nils-Halvdan Morken, Department of Public Health and Primary Health Care, University of Bergen, 5018 Bergen, Norway. E-mail: nils-halvdan.morken@kk.uib.no

Abstract

Objective

To estimate the risk of operative delivery according to maternal pre-pregnant body mass index (BMI) and gestational weight gain.

Design

Population-based pregnancy cohort study.

Setting

The Norwegian Mother and Child Cohort Study.

Sample

Term singleton deliveries in cephalic presentation, excluding preeclampsia, chronic hypertension, diabetes, gestational diabetes and placenta previa (= 50 416).

Methods

Relative risks (RR) were obtained using general linear models.

Main outcome measures

RR of operative vaginal delivery and cesarean section.

Results

Overweight and obese women had an increased risk of cesarean section, strongest for women with a pre-pregnancy BMI >40 (RR: 3.4, 95% confidence interval (CI): 2.8–4.1). There was also an increased risk of vacuum extraction delivery for women with a pre-pregnancy BMI >40 (RR: 1.5, 95% CI: 1.04–2.2). Women with a gestational weight gain of ≥16 kg had a significantly increased risk of forceps, vacuum extraction and cesarean section (RR: 1.2, 95% CI: 1.03–1.4, RR: 1.2, 95% CI: 1.1–1.23 and RR: 1.3, 95% CI: 1.26–1.4, respectively). Weight gain during pregnancy was significantly lower in obese women, but the children tended to be larger.

Conclusions

Obese women have an increased risk of operative delivery with vacuum extraction and cesarean section. Independently of pre-pregnancy BMI, we found an increased risk of operative intervention during delivery for women with gestational weight gain above 16 kg.

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