Trends of change in the individual contribution of risk factors for small for gestational age over more than 2 decades

Secular trends of low birth weight, preterm birth, and small for gestational age in Shanghai from 2004 to 2020: an age-period-cohort analysis

BACKGROUND

Although highly heterogeneous among countries, the incidence rates of low birth weight (LBW), preterm birth (PTB), and small for gestational age (SGA) have been increasing globally over the past two decades. To better understand the cause of these secular trends, this study aimed to investigate the effects of age, period, and birth cohort on LBW, PTB, and SGA rates in Shanghai.

METHODS

Data from 2,958,695 singleton live births at 24-41 gestational weeks between 2004 and 2020 were obtained for this study. Age-period-cohort models based on Poisson regression were used to evaluate the independent effects of maternal age, delivery period, and maternal birth cohort on the trends in LBW, PTB, and SGA.

RESULTS

The overall prevalence rates of LBW, PTB, and SGA were 2.9%, 4.7%, and 9.3%, respectively, and significant changes were observed (average annual change: + 10.7‰, + 9.1‰, -11.9‰) from 2004 to 2020. Cohort effect increased steadily, from 1960 (risk ratio [RR] = 0.71, 95% confidence interval [CI]: 0.65-0.78) to 1993 (RR = 0.97, 95% CI: 0.94-1.01) for LBW and from 1960 (RR = 0.69, 95% CI: 0.64-0.75) to 2004 (RR = 1.02, 95% CI: 0.94-1.12) for PTB. A strong cohort effect was found with the highest risk of SGA (RR = 1.82, 95% CI: 1.72-1.93) in 1960 and the lowest risk (RR = 0.57, 95% CI: 0.54-0.61) in 2004, compared with the reference cohort of 1985. There was a "U-shaped" maternal age effect on LBW and PTB and a weak period effect on the three birth outcomes.

CONCLUSIONS

Our findings suggested a significant independent effect of age, period, and birth cohort on the three birth outcomes. The increasing rates of LBW and PTB motivated us to focus on young and advanced pregnant women. Meanwhile, the prevalence of SGA decreased steadily, illustrating the need for further research on the mechanisms underlying these trends.

Risk factors of lower birth weight, small-for-gestational-age infants, and preterm birth in pregnancies following bariatric surgery: a scoping review

PURPOSE

Bariatric surgery increases the risk of lower birth weight, small-for-gestational-age (SGA) infants, and preterm birth in a subsequent pregnancy. However, the factors that contribute to these adverse birth outcomes are unclear. This review aimed to collate available information about risk factors of lower birth weight, SGA, and preterm birth following bariatric surgery.

METHODS

A literature search was conducted using five databases (PubMed, PsycINFO, EMBASE, Web of Science, and Cochrane Library) to obtain relevant studies.

RESULTS

A total number of 85 studies were included. Studies generally excluded surgery-to-conception interval, pregnancy complications, cigarette use, and maternal age as influencing factors of birth weight, SGA, or preterm birth. In contrast, most studies found that malabsorptive procedures, lower gestational weight gain, lower glucose levels, abdominal pain, and insufficient prenatal care were associated with an elevated risk of adverse birth outcomes. Findings were mixed regarding the effects of surgery-to-conception weight loss, pre-pregnancy body mass index, micronutrient deficiency, and lipid levels on birth outcomes. The examination of maternal microbiome profiles, placental function, alcohol use, and exercise was limited to one study; therefore, no conclusions could be made.

CONCLUSION

This review identified factors that appear to be associated (e.g., surgery type) or not associated (e.g., surgery-to-conception interval) with birth outcomes following bariatric surgery. The mixed findings and the limited number of studies on several variables (e.g., micronutrients, exercise) highlight the need for further investigation. Additionally, future studies may benefit from exploring interactions among risk factors and expanding to assess additional exposures such as maternal mental health.

Ability of municipality-level deprivation indices to capture social inequalities in perinatal health in France: A nationwide study using preterm birth and small for gestational age to illustrate their relevance

BACKGROUND

Evidence-based policy-making to reduce perinatal health inequalities requires an accurate measure of social disparities. We aimed to evaluate the relevance of two municipality-level deprivation indices (DIs), the French-Deprivation-Index (FDep) and the French-European-Deprivation-Index (FEDI) in perinatal health through two key perinatal outcomes: preterm birth (PTB) and small-for-gestational-age (SGA).

METHODS

We used two data sources: The French National Perinatal Surveys (NPS) and the French national health data system (SNDS). Using the former, we compared the gradients of the associations between individual socioeconomic characteristics (educational level and income) and "PTB and SGA" and associations between municipality-level DIs (Q1:least deprived; Q5:most deprived) and "PTB and SGA". Using the SNDS, we then studied the association between each component of the two DIs (census data, 2015) and "PTB and SGA". Adjusted odds ratios (aOR) were estimated using multilevel logistic regression with random intercept at the municipality level.

RESULTS

In the NPS (N = 26,238), PTB and SGA were associated with two individual socioeconomic characteristics: maternal educational level (≤ lower secondary school vs. ≥ Bachelor's degree or equivalent, PTB: aOR = 1.43 [1.22-1.68], SGA: (1.31 [1.61-1.49]) and household income (< 1000 € vs. ≥ 3000 €, PTB: 1.55 [1.25-1.92], SGA: 1.69 [1.45-1.98]). For both FDep and FEDI, PTB and SGA were more frequent in deprived municipalities (Q5: 7.8% vs. Q1: 6.3% and 9.0% vs. 5.9% for PTB, respectively, and 12.0% vs. 10.3% and 11.9% vs. 10.2% for SGA, respectively). However, after adjustment, neither FDep nor FEDI showed a significant gradient with PTB or SGA. In the SNDS (N = 726,497), no FDep component, and only three FEDI components were significantly associated (specifically, the % of the population with ≤ lower secondary level of education with both outcomes (PTB: 1.5 [1.15-1.96]); SGA: 1.25 [1.03-1.51]), the % of overcrowded (i.e., > 1 person per room) houses (1.63 [1.15-2.32]) with PTB only, and unskilled farm workers with SGA only (1.52 [1.29-1.79]).

CONCLUSION

Some components of FDep and FEDI were less relevant than others for capturing ecological inequalities in PTB and SGA. Results varied for each DI and perinatal outcome studied. These findings highlight the importance of testing DI relevance prior to examining perinatal health inequalities, and suggest the need to develop DIs that are suitable for pregnant women. .