Evidence map›Paper›PMID 42426698›Full record

Observational studyBMC public health2026

Body mass index and reported contraceptive use prior to the index pregnancy among Chinese women with unintended pregnancy: a multicenter cross-sectional analysis of a prospective cohort.

Lin Shen, Jie Li, Kaiyan Pei, Xue Jiang, Xiaomei Jiang, Lina Zhang, Zhonglan Xu, Xiuqing Zhang, Lixia Chen, Fengyan Ren and 4 more

Abstract readMulticenter StudyObservational Study
In one paragraph

Observational study in BMC public health, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

0numbers the graph read from it
0cells of the map it votes in
0citing papers in PubMed
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1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

0 citing papers in PubMed.

No citing paper in PubMed yet.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

14 authors.

Lin ShenNational Research Institute for Family Planning, Chinese Academy of Medical Sciences & Peking UnionMedical College, No. 12, Dahuisi Road, Haidian District, Beijing, 100081, China.
Jie LiDepartment of Obstetrics & Gynecology, Peking University First Hospital, Beijing, 100034, China.
Kaiyan PeiNational Research Institute for Family Planning, Chinese Academy of Medical Sciences & Peking UnionMedical College, No. 12, Dahuisi Road, Haidian District, Beijing, 100081, China. psmile1971@163.com.
Xue JiangNational Research Institute for Family Planning, Chinese Academy of Medical Sciences & Peking UnionMedical College, No. 12, Dahuisi Road, Haidian District, Beijing, 100081, China.
Xiaomei JiangNational Research Institute for Family Planning, Chinese Academy of Medical Sciences & Peking UnionMedical College, No. 12, Dahuisi Road, Haidian District, Beijing, 100081, China.
Lina ZhangChangzhou Maternal and Child Health Hospital, Changzhou, 213000, China.
Zhonglan XuYangzhou Maternal and Child Health Hospital, Yangzhou, 225000, China.
Xiuqing ZhangTaiyuan Maternal and Child Health Hospital, Taiyuan, 030012, China.
Lixia ChenZhangjiakou Maternal and Child Health Hospital, Zhangjiakou, 075000, China.
Fengyan RenDaqing People's Hospital, Daqing, 163000, China.
Xiuling GuoZaozhuang Maternal and Child Health Hospital, Zaozhuang, 277100, China.
Xiaowan LuoBoai Hospital of Zhongshan, Zhongshan, 528437, China.
Qiwei QiQingdao Maternal and Child Health Hospital, Qingdao, 266011, China.
Jun GeTanggu Maternal and Child Health Hospital, Tanggu, 300451, China.

Funding

the Non-profit Central Research Institute Fund of National Research Institute for Family Planning No. 2021GJZ02 and No. 2023GJZD01
6 · The paper itself

Abstract

backgroundUnintended pregnancy remains a major public health challenge globally and in China. While body mass index (BMI) is associated with adverse obstetric and metabolic outcomes, its relationship with contraceptive use among women with unintended pregnancy remains poorly characterized in large Chinese populations. This study investigated the cross-sectional association between BMI and reported contraceptive use prior to index pregnancy, and explored its clinical and public health implications.

methodsThis cross-sectional analysis utilized baseline data from a multicenter prospective cohort study conducted at 10 hospitals across 8 Chinese provinces and municipalities (May 2019-February 2022). A total of 8,125 women with unintended pregnancy were included. Multivariable logistic regression models were applied with BMI as both continuous and categorical variables (underweight, normal weight [reference], overweight, obese). Among contraceptive users, we further examined the association between BMI and the use of highly effective (HEC) versus less effective (LEC) contraception. Sensitivity analyses using random forest imputation and complete-case analysis were performed.

resultsAfter full adjustment, each 1-unit increase in BMI was associated with 2% lower odds of reported contraceptive use (OR = 0.98, 95% CI: 0.96-0.99; P = 0.003). Women with overweight (OR = 0.85, 95% CI: 0.74-0.98; P = 0.024) and obesity (OR = 0.75, 95% CI: 0.57-0.98; P = 0.035) had significantly lower odds of contraceptive use compared to women with normal weight, whereas no significant association was observed for women with underweight. Among contraceptive users, BMI showed no significant association with the use of highly effective contraception (HEC) versus less effective contraception (LEC), regardless of whether BMI was modeled as a continuous or categorical variable. These findings remained robust in sensitivity analyses.

conclusionsOverweight and obesity are independently associated with lower odds of contraceptive use among Chinese women with unintended pregnancy. These findings highlight the need for targeted contraceptive counseling for women with elevated BMI to reduce the burden of unintended pregnancy.

Indexed as

Body Mass IndexContraception BehaviorPregnancy, UnplannedAdolescentAdultChinaCross-Sectional StudiesFemaleHumansPregnancyProspective StudiesYoung AdultBody mass indexChinese populationsContraceptive useUnintended pregnancy

Identifiers

PMID42426698
PMCPMC13637314

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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.