Safety of low weight gain or weight loss in pregnancies with class 1, 2, and 3 obesity: a population-based cohort study
Authors' conclusion
Our findings support calls to lower or remove the lower limit of current IOM recommendations for pregnant women with obesity, and suggest that separate guidelines for class 3 obesity might be warranted.
Study context
- Population
- Singleton pregnancies with obesity (early pregnancy BMI ≥30 kg/m² before 14 weeks), delivered 2008–2015, Stockholm-Gotland Perinatal Cohort linked with Swedish national registerspregnancies with obesity
- Participants
- 15,760 pregnancies
- Exposure
- Gestational weight gain below Institute of Medicine (IOM) lower limit or weight loss vs IOM lower limit (5 kg at term), by obesity class
- Class 1 obesityn = 11,667
- Class 2 obesityn = 3,160
- Class 3 obesityn = 933
- Outcome
- Severity-weighted composite adverse outcome (stillbirth, infant death, LGA and SGA at birth, preterm birth, unplanned caesarean delivery, GDM, pre-eclampsia, excess postpartum weight retention, new-onset longer-term maternal cardiometabolic disease) along the weight gain z-score continuum vs IOM lower limit (5 kg at term)
- Follow-up
- Median 7.9 years (IQR 5.8-9.4)
Methodological detailsPoisson regression, severity-weighted composite outcome, adjusted for confounding factors
- Poisson regression
- Severity-weighted composite outcome
- Adjusted for confounding factors
Main finding
As reported in the abstract
Composite adverse outcome at weight gain z-score −2.4 (0 kg at 40 weeks) vs IOM lower limit
Adjusted relative risk (95% CI)
Class 1 obesityz-score −2.4vs IOM lower limit
0.97(0.89–1.06)
Class 2 obesityz-score −2.4vs IOM lower limit
0.96(0.86–1.08)
Class 3 obesityz-score −2.4 (0 kg)vs IOM lower limit
0.81(0.71–0.89)
Observational data: associations, not effects.
Further findings
Weight gain below IOM lower limit (5 kg)
Original publication
Safety of low weight gain or weight loss in pregnancies with class 1, 2, and 3 obesity: a population-based cohort study. Lancet. Published 28 March 2024. doi:10.
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