Are the metabolic changes of pregnancy reversible in the first year postpartum?

Maternal metabolic alterations are essential to achieve healthy pregnancy outcomes, but increasing maternal parity may be associated with long-term metabolic dysfunction risk. As existing data are limited by study design, our aim was to employ robust metabolic measures to determine whether or not physiological pregnancy alterations in maternal metabolic function persist at 1 year postpartum.

We evaluated 21 healthy women, of whom 11 had an interval pregnancy (IP) and assessment at preconception, during pregnancy and 1 year postpartum, and 10 had no IP and assessment at baseline and a 1 year interval. Assessment measures included body composition, insulin sensitivity and response, and basal metabolic rate. For each measure, IP vs no IP and time intervals within each group were compared using nonparametric analyses, reporting median (IQR).

IP and no IP women were similar at enrolment, and no IP women had similar metabolic profiles at enrolment and the 1 year interval. IP women exhibited expected metabolic changes during pregnancy compared with preconception. In IP women, preconception and postpartum measures, including fat mass (20.7 [13.7-37.4] kg vs 18.4 [13.8-41.3] kg; p = 0.2), total insulin response (AUC 11,459 [9,230-13,696] pmol/ml × min vs 11,522 [5,882-17,404] pmol/ml × min; p = 0.9), insulin sensitivity (0.12 [0.06-0.13] mg [kg fat-free mass (FFM)](-1) min(-1) vs 0.11 [0.10-0.15] mg [kg FFM](-1) min(-1); p = 0.1) and basal metabolic rate (0.092 [0.092-0.105] kJ min(-1) FFM vs 0.096 [0.088-0.096] kJ min(-1) FFM; p = 0.5), were similar.

Our findings suggest pregnancy might not irreversibly alter maternal metabolic profile, measured at preconception through to 1 year postpartum. This result might be explained by a return to pre-pregnancy weight.