Ying Yang

S: To identify associations between Hb concentration in different trimesters, Hb changes and Hb trajectories during pregnancy with risk of preterm birth (PTB) and low birth weight (LBW). A retrospective cohort study included 18 980 participants from Haidian District Maternal and Child Health Care Hospital from 2018–2021. Hb concentrations were measured at first (0–12 weeks), second (13–27 weeks) and third trimesters (≥ 28 weeks). Hb was categorised into four groups (< 110, 110–119, 120–129, ≥ 130 g/l), and Hb changes between trimesters were calculated. The latent class growth mixed model was employed to estimate Hb trajectories. Association assessment and dose–response relationship used logistic regression and restricted cubic spline. Compared with Hb 110–119 g/l, women with Hb ≥ 130 g/l significantly increased odds of PTB (OR: 1·74, 95 % CI 1·29, 2·31) and LBW (OR: 2·31, 95 % CI 1·65, 3·20) during the second trimester. In the third trimester, women with Hb 120–129 g/l showed 26 % (OR: 1·26, 95 % CI 1·04, 1·51) increased odds of PTB and 72 % (OR: 1·72, 95 % CI 1·36, 2·17) increased odds of LBW, while the OR of Hb ≥ 130 g/l for PTB and LBW were 1·45 (95 % CI 1·12, 1·86) and 2·60 (95 % CI 1·96, 3·43). Hb changes exhibited a linear increase in odds of PTB and LBW. Women with a decline-sharp-rise trajectory had a 1·48-fold odds of PTB (OR: 1·48, 95 % CI 1·26, 1·75), compared with a decline-gradual-rise trajectory. These findings underscore the importance of monitoring Hb during pregnancy.

Maternal preconception blood pressure (BP) is associated with various adverse pregnancy outcomes, but its relationship with spontaneous abortion (SA) remains controversial. We aimed to evaluate the relationship between preconception BP and SA. This population-based cohort study used data from participants in the National Free Preconception Examination Program between 2013 and 2019. Maternal preconception BP was categorized according to the 2017 ACC/AHA guidelines. The relationship between these BP categories and SA incidence was analyzed using multivariable logistic regression to generate adjusted odds ratios (aORs) with 95% confidence intervals (CIs). Additionally, restricted cubic splines were employed to assess the dose-response relationship between maternal BP and the risk of SA. The study included 7 067 998 women, of whom 208 508 (2.95%) experienced a SA. Maternal preconception elevated BP (aOR, 1.02; 95% CI: 1.00-1.05), stage 1 hypertension (aOR, 1.06; 95% CI: 1.04-1.08), and stage 2 hypertension (aOR, 1.25; 95% CI: 1.20-1.31) were all associated with an increased risk of SA, demonstrating a gradient relationship. Our results also show that there is a "J"-shaped dose-response relationship between maternal preconception BP and the risk of SA, with the lowest risk observed at a systolic BP of 110 mm Hg and a diastolic BP of 70 mm Hg. Sensitivity analyses excluding individuals with hypotension or self-reported hypertension yielded results consistent with the main analysis. Preconception elevated BP and stage 1 hypertension were associated with an increased risk of SA, although the strength of these associations was weaker than that observed for stage 2 hypertension. There was a "J"-dose-response relationship between maternal preconception BP and the risk of SA, with the lowest risk of SA at systolic BP of 110 mm Hg and diastolic BP of 70 mm Hg.

Preventing impaired fasting glucose (IFG) and diabetes mellitus (DM) among reproductive-age women is important for both maternal and infant health. Although secondhand smoke exposure increases DM risk, evidence on glycemic impact from a single predominant household source remains limited. In populations with marked sex disparities in smoking prevalence, spousal smoking often constitutes women's primary exposure source. We examined temporal associations between husbands' smoking patterns with incident IFG and DM among reproductive-age Chinese women. This prospective cohort analyzed 2,828,544 couples from China's National Free Preconception Checkup Project (2010-2020) with two preconception examinations (median interval: 2.12 years). We included non-smoking women aged 20-49 years without pre-diagnosed DM and fasting plasma glucose (FPG) <7.0 mmol/L at baseline. Husbands' smoking was categorized as consistently non-smoking, consistently smoking, ex-smoking, or newly smoking. For consistently smoking husbands, we assessed smoking intensity (cigarettes per day) and cumulative exposure (pack-years). Among 2,475,950 women with baseline normal glycemia, we examined incident IFG (FPG 5.6-6.9 mmol/L) and DM (FPG ≥7.0 mmol/L or self-reported). Among 352,594 women with baseline IFG, we examined glycemic progression to DM. Of women with baseline normal glycemia, 10.1% developed IFG and 1.0% developed DM. Among husbands, 62.7% were consistently non-smoking, 16.2% consistently smoking, 11.5% ex-smoking, and 9.6% newly smoking. Compared to women with consistently non-smoking husbands, those with consistently smoking (adjusted odds ratio (AOR) 1.07, 95% confidence interval (CI) 1.03-1.11), ex-smoking (AOR 1.12, 95% CI 1.08-1.17), and newly smoking husbands (AOR 1.17, 95% CI 1.12-1.22) had higher odds of DM. Dose-response relationships were observed for cumulative pack-years with both IFG and DM (both P trend<0.05). Among women with baseline IFG, husbands' smoking cessation was associated with lower odds of DM progression (AOR 0.91, 95% CI 0.84-0.99) compared with continued smoking. Husbands' smoking increased wives' IFG and DM risks with dose-response relationships for cumulative exposure. Among women with baseline IFG, spousal smoking cessation was associated with reduced odds of DM progression. Preconception examination is a critical teachable moment for family-based smoking cessation interventions to prevent dysglycemia. These findings support expanding smoke-free policies to private settings and implementing comprehensive household tobacco control strategies.

There is a lack of data on the optimal gestational weight gain (GWG) in twin pregnancies in China. A multicenter retrospective study was conducted, contain

Background: During preconception counselling, pregnant women who smoke are advised to quit smoking. While the adverse effects of paternal smoking on pregnancy and perinatal outcomes have been increasingly recognised, the health benefits of paternal smoking cessation prior to conception remain understudied. Methods: The current study involved non-smoking reproductive-aged Chinese women who participated two times in the National Free Prepregnancy Checkups Project during 2010–2018. A total of 158 986 pregnancies were included, with husbands reporting smoking at the preconception examination stage during their first participation. The primary exposure was paternal smoking cessation before pregnancy. And the primary outcome was spontaneous abortion (SAB) recorded in the second participation. Inverse-probability-weighted (IPW) logistic regression was used to estimate ORs and their 95% CIs of SAB with paternal smoking cessation before pregnancy. Instrumental variable (IV) analyses were further used to estimate the association. Results: Compared with continued paternal smoking, paternal smoking cessation before pregnancy was associated with a reduced risk of SAB (IPW-adjusted OR 0.86 (95% CI 0.81 to 0.91); IV-estimated OR 0.79 (95% CI 0.76 to 0.82)). Additionally, a decrease in paternal smoking was also associated with a lower risk of SAB. Notably, the risk of SAB was still higher than that of those without paternal smoking in IV analysis (OR 1.21 (95% CI 1.26 to 1.32)). Conclusions: Paternal smoking cessation prior to conception is linked to a reduced risk of SAB. However, the risk of SAB among women with paternal smoking cessation was still higher than that among those without paternal smoking. Preconception counselling should advise fathers who smoke to quit.

Epidemiologic evidence on thermal stress and preterm birth (PTB) is based on ambient temperature rather than a biothermal metric. Thyrotropin abnormalities have been associated with PTB and may increase thermal vulnerability. However, it remains unknown whether thermal stress and thyrotropin abnormalities synergistically contribute to increased risk of PTB. Here we conducted a nationwide cohort study among 6,218,131 singleton live births in China. Biothermal stress was measured using the Universal Thermal Climate Index. We found that both heat stress and cold stress during each trimester were associated with increased risks of PTB, with hazard ratios ranging from 1.06 (95% confidence interval [CI]: 1.05, 1.07) to 2.33 (95% CI: 2.30, 2.35) and from 1.08 (95% CI: 1.07, 1.09) to 1.68 (95% CI:1.67, 1.70), respectively. Participants with subnormal (<0.37 mIU/L) or supranormal thyrotropin levels (≥4.88 mIU/L) and biothermal stress had higher risks of PTB, compared with those with normal thyrotropin levels and non-thermal stress. Additive interactions were also identified between biothermal stress and thyrotropin abnormalities. We estimated that up to 13.52% of PTB were attributable to biothermal stress and thyrotropin abnormalities. Our study showed a synergistic effect of biothermal stress and preconceptional thyrotropin abnormalities, highlighting the importance of climate adaption measures and thyroid management toward pregnant women under climate change scenario.

Background: In addition to hyperglycemia, women with hypoglycemia identified during pregnancy have a higher risk of adverse pregnancy outcomes. However, there is limited evidence of the association between prepregnant hypoglycemia and adverse pregnancy outcomes in women without pre-existing diabetes. This study aims to explore the association between maternal preconception hypoglycemia and adverse pregnancy outcomes among childbearing-aged women in China. Methods and findings: This was a retrospective cohort study of the National Free Preconception Checkup Project (NFPCP), including women who were aged 20–49, successfully conceived within one year without multiple gestations, and had complete information on pregnancy outcomes. Maternal fasting plasma glucose (FPG) concentrations were analyzed in the preconception examination stage, and women were divided into normal (FPG 3.9 to P < 0.001), LBW by 8% (95% CI [1.03, 1.12], P = 0.001), SGA by 7% (95% CI [1.05, 1.08], P < 0.001), and birth defects by 21% (95% CI [1.06, 1.37], P = 0.004), while the ORs of medical abortion decreased by 6% (95% CI [0.91, 0.98], P = 0.002), miscarriage or early stillbirth by 5% (95% CI [0.92, 0.97], P < 0.001), macrosomia by 12% (95% CI [0.86, 0.90], P < 0.001), and LGA by 12% (95% CI [0.86, 0.89], P < 0.001) if mothers had a preconception hypoglycemia. The associations of maternal preconception hypoglycemia and adverse pregnancy outcomes varied among BMI groups. Among underweight women, preconception hypoglycemia was associated with a lower risk of medical abortion, miscarriage or early stillbirth, LGA, and PID, while overweight women had a lower risk of macrosomia and LGA. Moreover, a higher risk of miscarriage or early stillbirth and PTB was observed in obesity and underweight, respectively, in association with preconception hypoglycemia. Main limitations in the current study included the limited generalizability in other countries with varying disparities in healthcare and the lack of information on certain potential confounders (such as gestational complications and whether they received any related intervention after preconception examination). Conclusion: Preconception hypoglycemia was significantly associated with adverse pregnancy outcomes, and maternal preconception BMI could modify the association. In addition to paying attention to women with preconception hyperglycemia, our findings call for increased concern for women with hypoglycemia in preconception glycemic screening, with consideration of modified effects by preconception BMI, which might be worth exploring as a means to reduce adverse pregnancy outcomes.