The impact of obesity and overweight on maternal and fetal health with conservative preconception interventions: a structured narrative review.

PURPOSE: Overweight and obesity before pregnancy are associated with adverse maternal, pregnancy-related, and longer-term health outcomes. This review aimed to summarize recent evidence on preconception overweight and obesity and to synthesize findings on conservative preconception or interpregnancy interventions, including lifestyle, dietary, behavioral, weight-management, and supplementation-based strategies.

METHODS

A structured narrative review with a predefined database search was conducted. PubMed and Embase were searched for studies published between January 2019 and December 2023 using the search string (("obesity" OR "overweight") AND "preconception"). Due to heterogeneity in study design, populations, interventions, comparators, outcomes, and follow-up durations, findings were synthesized narratively rather than quantitatively. Thirteen studies were included: 11 intervention studies and 2 observational cohort studies retained as contextual evidence.

RESULTS

Observational evidence associated higher preconception BMI with adverse pregnancy-related outcomes, including labor induction, cesarean delivery, preterm birth, neonatal care admission, stillbirth, and post-delivery dysglycemia. Conservative interventions showed heterogeneous effects. Preconception weight loss was associated with selected fertility-related and glucose-related benefits in some studies, including shorter time to pregnancy after a very-low-energy diet intervention and lower odds of recurrent gestational diabetes mellitus when meaningful weight loss was achieved. Supplementation-based interventions showed inconsistent findings across BMI subgroups. Safety-related outcomes varied between studies, and long-term follow-up suggested that sustained benefits may depend on successful weight loss and maintenance of behavioral change.

CONCLUSIONS

Conservative preconception interventions may provide selected benefits for women with overweight or obesity, particularly when clinically meaningful weight loss is achieved. However, current evidence remains heterogeneous and does not define a single optimal intervention model, timing, or universal weight-loss target.