Women who followed a combination of five or more lifestyle factors, including changing specific aspects of their diets, experienced more than 80 percent less relative risk of infertility due to ovulatory disorders compared to women who engaged in none of the factors, according to a paper published in the Nov. 1 issue of Obstetrics & Gynecology. The study was led by researchers at the Harvard School of Public Health (HSPH) and did not examine risk associated with other kinds of infertility, such as low sperm count in men.
“The key message of this paper is that making the right dietary choices and including the right amount of physical activity in your daily life may make a large difference in your probability of becoming fertile if you are experiencing problems with ovulation,” said Walter Willett, senior author and chair of the HSPH Department of Nutrition. The lead author is Jorge Chavarro, research fellow in the HSPH Department of Nutrition. Both scientists have earned MDs and have appointments at Harvard Medical School.
Infertility affects one in six couples, according to studies in the United States and Europe. Ovulatory problems have been identified in 18 to 30 percent of those cases.
The researchers followed a group of 17,544 married women who were participants in the Nurses’ Health Study II based at the Brigham and Women’s Hospital. The team devised a scoring system on dietary and lifestyle factors that previous studies have found to predict ovulatory disorder infertility. Among those factors were:
- The ratio of mono-unsaturated to trans fats in diet
- Protein consumption (derived from animals or vegetables)
- Carbohydrates consumption (including fiber intake and dietary glycemic index)
- Dairy consumption (low- and high-fat dairy)
- Iron consumption
- Multivitamin use
- Body mass index (BMI, weight in kilograms divided by the square of height in meters)
- Physical activity
The researchers assigned a “fertility diet” score of one to five points. The higher the score, the lower the risk of infertility associated with ovulatory disorders.
The women with the highest fertility diet scores ate less trans fats and sugar from carbohydrates, consumed more protein from vegetables than from animals, ate more fiber and iron, took more multivitamins, had a lower body mass index (BMI), exercised for longer periods of time each day, and, surprisingly, consumed more high-fat dairy products and less low-fat dairy products. The relationship between a higher “fertility diet” score and lesser risk for infertility was similar for different subgroups of women regardless of age and whether or not they had been pregnant in the past.
Said Chavarro, “We analyzed what happens if you follow one, two, three, four, or more different factors. What we found was that as women started following more of these recommendations their risk of infertility dropped substantially for every one of the dietary and lifestyle strategies undertaken. In fact, we found a sixfold difference in ovulatory infertility risk between women following five or more low-risk dietary and lifestyle habits and those following none.”