Fertility Peaks Around Age 30 for Both Males and Females, Study Finds.

A new study co-authored by researchers from the Boston University School of Public Health found that fertility peaks around age 30 for men and women, and declines slightly later than suggested in previous studies.

(Flickr Photo/Esther Gibbons)The study found that among females, declines in fertility were not pronounced until after age 35; women aged 35-40 had 23 percent less chance of conceiving in each menstrual cycle than women aged 20-24. Males had a later and smaller decline in fertility than females, with only a 5% reduction among men aged 35-39. Some of the decline in fertility at older ages was offset by independent volitional factors affecting conception, such as frequency and timing of intercourse.

Despite the somewhat more optimistic view of age-related fertility than in prior studies, the study notes that “couples will experience a compounded effect of their separate age-related declines.” For example, if both partners are the same age, “then their fecundability at age 40 years is nearly half of what it is at age 30 years.”

Most previous studies have been conducted among fertility-clinic populations or populations using natural family planning, whereas this study was conducted in a population of Danish women with no known fertility problems

The study, called Snart Gravid, or ‘Soon Pregnant’, is a collaboration between researchers at BUSPH and the University of Aarhus in Denmark. Data for the study, based in Denmark, are collected via the internet and include questions on socio-demographic background, reproductive and medical history, as well as follow-up questions on pregnancy status, frequency and timing of intercourse, and other lifestyle factors. More than 3,700 women, aged 18 to 40, were enrolled.

Kenneth Rothman, professor of epidemiology at BUSPH, was lead author on the study. Other authors of the study included: Elizabeth Hatch, Lauren Wise, and Henrik Toft Sørensen of the BUSPH Department of Epidemiology; and Ellen M. Mikkelsen and Anders H. Riis of the Department of Clinical Epidemiology at Aarhus University Hospital in Denmark.

The study was supported by the National Institute of Child Health and Human Development and the Danish Medical Research Council. The research team recently launched a new study here in the United States, called PRESTO. Researchers are looking for female participants who are age 21-45, residents of Massachusetts, and not currently using any methods to prevent pregnancy.

For more information about the study, please visit: sites.bu.edu/presto