Plasma glycemic measures and fecundability in a Singapore preconception cohort study

Higher plasma glycemia during preconception, particularly fasting glucose, is associated with reduced fecundability and prolonged time to pregnancy, even within the normal range of glucose concentrations.

VOLUME 115, ISSUE 1, P138-147


See Ling Loy, Ph.D., Chee Wai Ku, M.R.C.O.G., Ada En Qi Lai, Xin Hui Choo, Angela Hui Min Ho, Yin Bun Cheung, Ph.D., Keith M. Godfrey, Ph.D., Yap-Seng Chong, M.R.C.O.G., Peter D. Gluckman, D.Sc., Lynette Pei-Chi Shek, F.R.C.P.C.H., Kok Hian Tan, F.R.C.O.G., Fabian Kok Peng Yap, F.R.C.P.C.H., Shiao-Yng Chan, F.R.C.O.G., Ph.D., Jerry Kok Yen Chan, F.R.C.O.G., Ph.D.



To examine the association between plasma glycemia in women attempting to conceive and fecundability, as measured by time to pregnancy.


Prospective preconception population-based study.




Asian preconception women, 18–45 years old, attempting conception for ≤12 cycles at study entry.



Main Outcome Measure(s)

We ascertained time to pregnancy within a year of glycemic assessment in menstrual cycles. We estimated fecundability ratios (FRs) and 95% confidence intervals using discrete-time proportional hazards models, adjusting for age, ethnicity, education, body mass index, and cycle regularity and accounting for left truncation and right censoring.


We studied a population sample of 766 women from the Singapore Preconception Study of Long-Term Maternal and Child Outcomes prospective cohort. Compared with women with normoglycemia, women with dysglycemia (prediabetes and diabetes, defined by the American Diabetes Association) had a lower FR (0.56). Compared with the respective lowest quintiles, women in the highest quintile of fasting glucose (≥5.1 mmol/L) had an FR of 0.60, while women in the highest 2-hour postload glucose quintile (≥6.9 mmol/L) had an FR of 0.66. Overall, the FRs decreased generally across the range of fasting and 2-hour plasma glucose. Glycated hemoglobin was not associated with fecundability.


Increasing preconception plasma glucose is associated with reduced fecundability, even within the normal range of glucose concentrations.

Clinical Trial Registration Number