Flowchart in the selection of study participants.

Previous studies have shown that interpregnancy weight fluctuations impact perinatal outcomes. In order to examine this in Japanese women, we analyzed the data of 2,861 women in their first and second pregnancies who delivered singletons between 2000 and 2022. We compared the second pregnancy perinatal outcomes of women whose interpregnancy body mass index (BMI) change was -1 to 1 unit with those of women whose BMI change was 2 before their first pregnancy were associated with a remarkable risk reduction of developing gestational diabetes mellitus (aOR, 0.33; 95% CI, 0.12–0.88). Weight gain during interpregnancy period was related to an increased risk of gestational diabetes mellitus and delivery of a large-for-gestational-age neonate, whereas weight loss was related to a decreased risk of developing gestational diabetes mellitus. These results indicate the importance of interpregnancy weight control as part of preconception care; therefore, women considering additional pregnancies should be educated on the importance of maintaining a healthy weight.</div

STROBE statement—checklist of items that should be included in reports of observational studies.

STROBE statement—checklist of items that should be included in reports of observational studies.</p

Adjusted odds ratios for adverse perinatal outcomes during the second pregnancy in relation to interpregnancy BMI changes.

Adjusted odds ratios for adverse perinatal outcomes during the second pregnancy in relation to interpregnancy BMI changes.</p

Adjusted odds ratios for adverse perinatal outcomes during the second pregnancy in relation to interpregnancy BMI changes between the first and second pregnancy stratified by prepregnancy BMI at the first pregnancy.

Adjusted odds ratios for adverse perinatal outcomes during the second pregnancy in relation to interpregnancy BMI changes between the first and second pregnancy stratified by prepregnancy BMI at the first pregnancy.</p

Maternal characteristics and perinatal outcomes at the first and second pregnancy.

Maternal characteristics and perinatal outcomes at the first and second pregnancy.</p

Participants classified by interpregnancy BMI changes and maternal characteristics and perinatal outcomes at first pregnancy.

Participants classified by interpregnancy BMI changes and maternal characteristics and perinatal outcomes at first pregnancy.</p

Comparison of maternal characteristics between pre-pregnancy underweight, normal weight, overweight and obese women.

<p>Comparison of maternal characteristics between pre-pregnancy underweight, normal weight, overweight and obese women.</p

Pregnancy outcomes for overweight women in reference to weight gain.

<p>Pregnancy outcomes for overweight women in reference to weight gain.</p

Flow diagram of study inclusion.

<p>^aBMI, body mass index; ^bGWG, gestational weight gain.</p

Pregnancy outcomes for underweight women in reference to weight gain.

<p>Pregnancy outcomes for underweight women in reference to weight gain.</p