Pre-Pregnancy Health Status and Risk of Preterm Birth: A Large, Chinese, Rural, Population-Based Study

Abstract

The aim of this study was to estimate the incidence of preterm birth (PTB) and identify maternal risk factors before pregnancy in rural China, and to determine their population-attributable fractions (PAFs).A prospectively population-based study was conducted in the city of Fuyang, China. Surveillance locations were randomly selected by cluster sampling based on administrative areas and geographic characteristics. Data were collected through interview questionnaires and medical examination records from the participants, then follow-up until discharge, fetus death, or at a maximum of 6 weeks postpartum, whichever came first. We used logistic regression analysis to identify the associated factors. PAFs were also estimated to examine the impact of risk factors.The incidence of PTB was 3.86% in this study. Multivariate analyses showed that risk factors for PTB were economic pressure (aOR=2.98, 95% CI, 2.40–3.71), hypertension (aOR=3.45, 95% CI, 2.23–5.36), hypoglycemia (aOR=2.07, 95% CI, 1.58, 2.72), hyperglycemia (aOR=1.69, 95% CI, 1.09, 2.62), serum creatinine (<44 μmol/L) (aOR=1.78, 95% CI, 1.13–2.40), hypothyroidism (aOR=1.37, 95% CI, 1.06–1.78), positivity for anti-CMV IgM (aOR=2.57, 95% CI, 1.21–5.45), multiple pregnancy (aOR=3.35, 95% CI, 1.87–6.00), and parity (≥3 times) (aOR=1.67, 95% CI, 1.05–2.64). Economic pressure was the most significant contributor (11.57%), while parity was the lowest (0.10%).This study demonstrated the relatively high burden of PTBs in a rural Chinese area. A broader focus on the risk factors prior to pregnancy amenable to interventions of women may reduce the incidence of PTB.

Prepregnancy Glucose Levels Within Normal Range and Its Impact on Obstetric Complications in Subsequent Pregnancy: A Population Cohort Study

“… 10 A prospective study examined the relationship between prepregnancy maternal factors and obstetric outcomes that fasting blood sugar of more than 6.1 mmol/L (108.9 mg/dL) was associated with increased preterm birth after adjustment. 11 Another recent study on prepregnancy IFG was a retrospective cohort study what revealed IFG increased the risk of preterm birth, LGA and severe LGA. 12 …”

The impact of maternal prepregnancy impaired fasting glucose on preterm birth and large for gestational age: a large population-based cohort study

“…To our knowledge, only 2 studies among the few studies pertaining to prepregnancy IFG and adverse pregnancy outcomes. 30,31 Salman et al 30 analyzed singleton pregnancies of 1945 women in Israel, but the authors found the association of prepregnancy IFG only with the abnormal glucose challenge test and gestational diabetes mellitus (GDM), rather than with an increased risk of PTB and LGA.…”

“…Hu et al 31 conducted a prospective study of 16,890 women in central China to estimate the incidence of PTB and identify maternal risk factors before pregnancy from 2010 to 2013. Although they found that women with prepregnancy hyperglycaemia (FBG level >6.1 mmol/L) had an increased risk of PTB compared with women with normoglycaemia (3.9 mmol/L or greater and 6.1 mmol/L or less) after adjustment (6.3% vs 3.6%, aOR, 1.69, 95% CI, 1.09e2.62), the definition of hyperglycemia in this study was unclear, which reduced the strength of the study.…”

“…Although they found that women with prepregnancy hyperglycaemia (FBG level >6.1 mmol/L) had an increased risk of PTB compared with women with normoglycaemia (3.9 mmol/L or greater and 6.1 mmol/L or less) after adjustment (6.3% vs 3.6%, aOR, 1.69, 95% CI, 1.09e2.62), the definition of hyperglycemia in this study was unclear, which reduced the strength of the study. 31 The discrepancies of the associations of IFG or hyperglycemia both before and during pregnancy with the risk of PTB and LGA might be related to the measurement of blood glucose and the threshold for hyperglycaemia. Evidence from the recent meta-analyses showed that there was a positive linear association with LGA for all glucose exposures across the distribution of glucose concentrations during pregnancy, and no clear evidence of a threshold.…”

Nomogram to predict the risk of preterm birth before 37 weeks and 34 weeks in pregnant women with a short cervix: a retrospective cohort study

“…Of note, we found that autoimmune disease (SLE and APS) increased the risk of PTB < 37 weeks 13 . However, PCOS and hypothyroidism previously associated with PTB were not significantly correlated with occurrence of PTB 18,19 . In the current study, prepregnancy hypertension was associated with PTB < 34 weeks but not PTB < 37 weeks.…”