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Reproductive Endocrinology

MON-123 - The Preconception Lifestyle and Nutrition (PLAN) Study: A randomized controlled trial assessing maternal and neonatal outcomes

Monday, June 15, 2026
9:00 AM - 2:00 PM CT
Disclosure(s):
Amy E. Rothberg, MD: No financial relationships to disclose
William H. Herman, MD, MPH: No financial relationships to disclose


Introduction: Obesity is common in reproductive age women and during pregnancy, is associated with complications for the mother and the neonate. We hypothesized that an intensive lifestyle intervention implemented before conception might offset the deleterious effects of maternal obesity.

Materials and

Methods: Women with obesity were randomized to 3 months of standard of care (SOC) dietary advice or to very low energy diet (VLED) before conception. Normal weight women (LEAN) were also studied.

Results: The study included 27 women randomized to SOC, 21 randomized to VLED, and 35 LEAN controls and their neonates. SOC lost 2.1 kg and VLED lost 11.2 kg before conception. VLED gained more weight during pregnancy (16.8 kg) than SOC (12.5 kg) although net weight change between baseline and delivery was least in VLED (5.6 kg), intermediate in SOC (10.5 kg) and greatest in LEAN (14.0 kg). ). The incidence of gestational hypertension tended to be greater in SOC compared to VLED mothers. Abdominal circumference percentile (AC%) at 18 weeks was no different among the groups, but AC% at term tended to be greatest for VLED fetuses and neonate weight-for-gestational-age z-score was significantly greater in VLED compared to SOC neonates. Percent body fat was also significantly greater in VLED neonates compared to SOC neonates.

Discussion: Despite reductions in maternal preconception weight, neonatal biometric outcomes did not approximate the LEAN and were not improved in neonates of mothers with obesity randomized to VLED compared to SOC. Although feasible and effective, an intensive preconception lifestyle intervention did not reduce newborn size or adiposity compared to SOC. Additional studies are needed to understand the impact of preconception weight loss, gestational weight gain, and gestational hypertension on the developmental origins of health and disease.

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