Family, friends, and online sources can provide advice on how to have a healthy pregnancy, but how do couples know what is based on scientific evidence? NIEHS has several researchers who study the topic, and one of them has been recognized by the Society for Epidemiologic Research (SER) for his exemplary career.
Allen Wilcox, M.D., Ph.D., head of the NIEHS Reproductive Epidemiology Group, received the 2018 Kenneth Rothman Career Accomplishment Award during the SER Annual Meeting in Baltimore June 19-22. The award, which carries a $2,000 prize, honors the nearly 40 years Wilcox has spent at NIEHS working on the mechanisms of human reproduction.
'Constructive criticism is a necessary part of research. It’s not so often that we hear someone say 'nice job',' Wilcox said. 'To hear that from my colleagues is the best reward I could get.'
Early findings gain national attention
When Wilcox came to NIEHS in 1979, there were not many epidemiologists doing research on fertility and pregnancy. One of his first studies was the Early Pregnancy Study, which initially measured pregnancy loss that occurred before women knew they were pregnant. To do it, Wilcox and his team had to measure women’s urine each day for the presence of human chorionic gonadotropin, commonly called the pregnancy hormone. The study began in the early 1980s, before home pregnancy kits were commercially available.
One challenge was to find women who were planning to get pregnant and willing to collect daily urine samples. Although it took three and a half years to enroll 221 women, Wilcox was finally ready to begin.
Fellow NIEHS scientists Donna Baird, Ph.D., and Clarice Weinberg, Ph.D., were part of the research team that analyzed approximately 28,000 urine samples. What they found was astonishing. Twenty-four percent of detectable pregnancies ended very early. Another nine percent ended in clinically recognized miscarriage, meaning one in three failures.
'We asked women to fill out a daily record card and to note if they thought they were pregnant,' Wilcox said. 'Almost all of these losses occurred without women having any idea they had conceived.'
The results were published in the prestigious New England Journal of Medicine in 1988 and generated a lot of media coverage. Incredibly, Wilcox and colleagues are still publishing papers using the original data. Journal articles resulting from the Early Pregnancy Study number more than 50 and have appeared in major clinical, statistical, and epidemiologic journals.
According to SER President Andrew Olshan, Ph.D., the Society could not have made a better choice for this year’s career accomplishment winner. 'Dr. Wilcox is a truly outstanding epidemiologist, an internationally recognized scholar, who has made extraordinary contributions to the field of epidemiology,' he said.
Most women do not know when they ovulate, or release an egg from the ovaries, but it is the most important event in the menstrual cycle. It is the time that conception occurs, if sperm are present. Once Baird figured out how to identify the day of ovulation using hormones in urine, and Weinberg developed the statistical methods, the team could determine the women’s fertile days in their menstrual cycle.
It turns out that women are fertile for five days before they ovulate and on the day of ovulation, but not afterward. If a woman only has intercourse the day after she ovulates, it is too late.
Advances in fetal development
Wilcox is also interested in what affects a fetus during pregnancy and how those impacts affect the child’s health later. He was the first to demonstrate that pregnant women exposed to secondhand cigarette smoke could increase their risk of having a child with a facial cleft.
His work with Norwegian health registries allowed him and his collaborators to be the first to detail familial risk of birth defects on a population level. His recent research examines cerebral palsy, which has its origins during fetal life.
Citation: Wilcox AJ, Weinberg CR, O’Connor JF, Baird DD, Schlatterer JP, Canfield RE, Armstrong EG, Nisula BC. 1988. Incidence of early loss of pregnancy. N Engl J Med 319(4):189−194.