OBJECTIVE

To study the association between prepregnancy subnormal body weight and obstetrical outcomes after autologous in vitro fertilization (IVF) cycles.

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S): Women with prepregnancy subnormal body weight (body mass index <18.5 kg/m) and normal body weight (body mass index 18.5-25 kg/m) after assisted reproductive treatment.

INTERVENTIONS(S): None.

MAIN OUTCOME MEASURE(S): Clinical pregnancy rate (CPR), live birth rate (LBR), and miscarriage rate. CPR and LBR were calculated at per-woman and per-cycle levels.

RESULT(S): A total of 38 cohort studies with low risk of bias were included. Meta-analyses showed that, compared with normal-weight women, those underweight before pregnancy had a lower CPR at per-woman and per-cycle levels. Compared with normal weight, underweight before pregnancy had little impact on LBR at both per-woman and per-cycle levels, nor on miscarriage rate.

CONCLUSION(S): Compared with women of normal weight, women who were underweight before pregnancy had modest association with a lower CPR, but underweight did not seem to affect LBR or miscarriage after IVF.