Obesity prevalence rises fastest during young adulthood when weight, diet, and physical activity may be influenced by life events, including becoming a parent, but the impact is uncertain. We searched six electronic databases to July 2019 for longitudinal studies (both sexes) aged 15 to 35 years with a prospective pre‐pregnancy/parenthood and post‐delivery outcome. Of 11 studies (across 15 papers), six studies (women only) were eligible for meta‐analysis of the difference in change in body mass index (BMI; kg/m²) between remaining without children and becoming a parent. Mean (±SD) BMI gain for non‐mothers was 2.8 ± 1.3 kg/m² (~7.5 kg for 164‐cm woman) over 5.6 ± 3.1 years; 12.3% of baseline BMI (22.8 ± 2.5 kg/m²). Becoming a mother was associated with an additional BMI increase of 0.47 ± 0.26 kg/m² (~1.3 kg), 4.3% of baseline BMI (22.8 ± 5.6 kg/m²); the one study including men reported no difference in change. Physical activity results were equivocal; 2/4 studies (women) and 2/2 (men) showed a greater decline in parents versus non‐parents; diet (three studies) varied by dietary measure, mostly indicating no difference. Becoming a mother is associated with 17% greater absolute BMI gain than remaining childless. Motherhood BMI gain is additional to an alarming BMI increase among young women, highlighting the need for obesity prevention among all young women, including mothers.

中文翻译：

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成为父母：对 BMI、饮食和身体活动变化的系统回顾和荟萃分析。

肥胖患病率在成年早期上升最快，此时体重、饮食和身体活动可能会受到生活事件（包括成为父母）的影响，但其影响尚不确定。我们检索了截至 2019 年 7 月的 6 个电子数据库，以查找年龄为 15 至 35 岁的纵向研究（男女），并预测怀孕前/为人父母和分娩后的结果。在 11 项研究（涵盖 15 篇论文）中，有 6 项研究（仅限女性）符合对没有孩子和成为父母之间体重指数（BMI；kg/m ² ）变化差异进行荟萃分析的资格。在 5.6 ± 3.1 年内，非母亲的平均 BMI 增加为 2.8 ± 1.3 kg/m ²（164 厘米女性约为 7.5 kg）；基线 BMI 的 12.3% (22.8 ± 2.5 kg/m ² )。成为母亲与 BMI 额外增加 0.47 ± 0.26 kg/m ² (~1.3 kg) 相关，是基线 BMI (22.8 ± 5.6 kg/m ² ) 的 4.3%；一项包括男性在内的研究报告称变化没有差异。体力活动结果模棱两可；2/4（女性）和 2/2（男性）的研究表明，有父母的人与无父母的人相比，下降幅度更大；饮食（三项研究）因饮食测量而异，大多数表明没有差异。成为母亲后，BMI 绝对值比不生孩子增加 17%。年轻女性的体重指数令人震惊地增加，母亲的体重指数也随之增加，这凸显了包括母亲在内的所有年轻女性预防肥胖的必要性。