Background Studies have reported an increased risk of adverse pregnancy outcome associated with pre-pregnancy body mass index (BMI). However, the data on such associations in urban areas of southern Chinese women is limited, which drive us to clarify the associations of pre-pregnancy BMI and the risks of adverse pregnancy outcomes (preterm birth (PTB) and low birth weight (LBW)) and maternal health outcomes (gestational hypertension and cesarean delivery). Methods We performed a hospital-based case-control study including 3,864 Southern Chinese women who gave first birth to a live singleton infant from January 2015 to December 2015. PTB was stratified into three subgroups according to gestational age (extremely PTB, very PTB and moderate PTB). Besides, we combined birth weight and gestational age to dichotomise as being small for gestational age (SGA, less than the tenth percentile of weight for gestation) and non-small for gestational age (NSGA, large than the tenth percentile of weight for gestation), gestational week was also classified into categories of term, 34-36 week and below 34 week.. We then divided newborns into six groups: (1) term and NSGA; (2) 34–36 week gestation and NSGA; (3) below 34 week gestation and NSGA; (4) term and SAG; (5) 34–36 week gestation and SAG; (6) below 34 week gestation and SAG. Adjusted logistic regression models was used to estimate the odds ratios of adverse outcomes. Results Underweight women were more likely to give LBW (AOR = 1.44, 95% CI [1.11–1.89]), the similar result was seen in term and SAG as compared with term and NSAG (AOR = 1.78, 95% CI [1.45–2.17]), whereas underweight was significantly associated with a lower risk of gestational hypertension (AOR = 0.45, 95% CI [0.25–0.82) and caesarean delivery (AOR = 0.74, 95% CI [0.62–0.90]). The risk of extremely PTB is relatively higher among overweight and obese mothers in a subgroup analysis of PTB (AOR = 8.12, 95% CI [1.11–59.44]; AOR = 15.06, 95% CI [1.32–172.13], respectively). Both maternal overweight and obesity were associated with a greater risk of gestational hypertension (AOR = 1.71, 95% CI [1.06–2.77]; AOR = 5.54, 95% CI [3.02–10.17], respectively) and caesarean delivery (AOR = 1.91, 95% CI [1.53–2.38]; AOR = 1.85, 95% CI [1.21–2.82], respectively). Conclusions Our study suggested that maternal overweight and obesity were associated with a significantly higher risk of gestational hypertension, caesarean delivery and extremely PTB. Underweight was correlated with an increased risk of LBW and conferred a protective effect regarding the risk for gestational hypertension and caesarean delivery for the first-time mothers among Southern Chinese.

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Background: The purpose of the present study is to evaluate the effect of body mass index (BMI) on cycle characteristics and in vitro fertilization / intracytoplasmic sperm injection (IVF / ICSI) outcomes of a long down-regulation protocol in Southern Han Chinese women. Methods : This retrospective, observational study included 5279 infertile women undergoing IVF / ICSI cycle with a long down-regulation protocol. All the patients were divided into four subgroups by the recommended Chinese BMI cut-off points: underweight, BMI < 18.5 kg/m 2 ; normal-weight, 18.5 kg/m 2 ≤ BMI < 24.0 kg/m 2 ; overweight, 24.0 kg/m 2 ≤ BMI < 28.0 kg/m 2 ; obese, BMI ≥ 28.0 kg/m 2 . The demographic data and biochemical tests of patients, the parameters related to the ovarian responsiveness to gonadotrophin stimulation, IVF / ICSI treatment characteristics and pregnancy outcomes (clinical pregnancy rate, spontaneous abortion rate and lived birth rate) were compared among BMI categories. Results: The overweight patients had lower ovarian sensitivity index (OSI) ( P < 0.05) and higher spontaneous abortion rate than women in the normal-weight (13.59% vs. 10.28%, OR = 2.37, 95% CI: 1.35 – 4.16, P = 0.003 ). The overweight and obese patients seemed to have lower clinical pregnancy rate and live birth rate, but the difference was not statistically significant ( P > 0.05). Conclusion: This study provides new epidemiological clues that the elevated BMI might increase the risk of spontaneous abortion and impair ovarian response to gonadotropin stimulation during IVF / ICSI treatment.

Objectives The purpose of the present study is to evaluate the effect of body mass index (BMI) on cycle characteristics and in vitro fertilization / intracytoplasmic sperm injection (IVF / ICSI) outcomes of a long down-regulation protocol in Southern Han Chinese women. Methods This retrospective, observational study included 5279 infertile women undergoing IVF / ICSI cycle with a long down-regulation protocol. All the patients were divided into four subgroups by the recommended Chinese BMI cut-off points: underweight, BMI < 18.5 kg/m2; normal-weight, 18.5 kg/m2 ≤ BMI < 24.0 kg/m2; overweight, 24.0 kg/m2 ≤ BMI < 28.0 kg/m2; obese, BMI ≥ 28.0 kg/m2. The demographic data and biochemical tests of patients, the parameters related to the ovarian responsiveness to gonadotrophin stimulation, IVF / ICSI treatment characteristics and pregnancy outcomes (clinical pregnancy rate, spontaneous abortion rate and lived birth rate) were compared among BMI categories. Results The overweight and obese infertile patients required more priming gonadotropin, total gonadotropin and longer stimulation duration, and had the lower ovarian sensitivity index (OSI), lower serum progestogen (P) and estrogen (E2) on the day of HCG administration compared with the normal-weight women (P < 0.05). The overweight and obese patients had a higher spontaneous abortion rate than women in the normal-weight (13.59% vs. 10.28%, OR = 1.40, 95% CI: 1.02 - 1,90, P = 0.036; 17.58% vs.10.28%, OR = 1.92, 95% CI: 1.09 - 3.36, P = 0.023, respectively). The overweight and obese patients seemed to have lower clinical pregnancy rate and live birth rate, but the difference was not statistically significant (P > 0.05). Conclusion This study provides new epidemiological clues that the elevated BMI might impair ovarian response to gonadotropin stimulation and increase the risk of spontaneous abortion during IVF / ICSI treatment.