Female fecundability is associated with pre-pregnancy allostatic load: Analysis of a Chinese cohort

Allostatic load (AL) is a practical index that reflects multi-system physiological changes which occur in response to chronic psychosocial stress. This study investigated the association between female pre-pregnancy allostatic load and time to pregnancy.

We enrolled 444 women who met the inclusion criteria and were attempting to achieve pregnancy. Their allostatic load scores at baseline were evaluated by nine indicators (systolic blood pressure, diastolic blood pressure, fasting plasma glucose, plasma cortisol, noradrenaline, interleukin-6, hypersensitive C-reactive protein, high density lipoprotein cholesterol and body mass index). The participants were followed up and their pregnancy outcome ascertained 1 year later; we then calculated time-to-pregnancy. Cox models were used to estimate fecundability ratios and their 95% confidence intervals (95% CI) for different allostatic load scores.

The median allostatic load score was 1 with a range of 0-6. The females were divided into four groups according to allostatic load score: group A (allostatic load = 0, 150/444, 33.8%), group B (allostatic load = 1-2, 156/444, 35.1%), group C (allostatic load = 3-4, 100/444, 22.5%) and group D (allostatic load = 5-6, 38/444, 8.6%). The cumulative pregnancy rate over 12 months for the four groups (A-D) was 55.4%, 44.5%, 50.9% and 26.9%, respectively (log-rank test, p = 0.042). After adjusting for potential confounding factors, group D showed a 59% reduction of fecundability compared with group A (fecundability ratio = 0.41, 95% CI 0.21-0.83).

Women with a higher allostatic load score may have lower fecundability. Our findings suggest that the assessment of allostatic load during pre-conception consultation would be highly prudent.