Fertility is defined as “the natural capability to produce offspring”. There is little evidence on the impact prenatal vitamins have on the natural capability in producing offspring. However, scientific evidence that does exist demonstrates the role prenatal vitamins have on a healthier pregnancy with better birth outcomes and less comorbidities.
Although not a prenatal vitamin, taking a multivitamin has been associated with an increase in fertility. In a large prospective survey examining 116,671 nurses who have been followed and surveyed since 1989, the researchers found a protective association of fertility. The researches analyzed the data and excluded any confounding factors and found that the use of a multivitamin at least three times per week was associated with a decreased risk of ovulatory infertility, which resulted in more pregnancies.
During a pregnancy the need for vitamins and minerals increases and taking prenatal vitamins is one method in meeting this need. Prenatal vitamins are recommended by health practitioners for the positive effects they have on a pregnancy, not for increasing the rate or a chance of a pregnancy. The United States Department of Agriculture (USDA) has established many of the daily vitamin and mineral recommendations. These recommendations are used as guidelines for the different types of prenatal vitamins women take before and during pregnancy.
Some of the benefits of taking prenatal vitamins occur before a woman becomes pregnant. One of the best examples for taking prenatal vitamins prior to becoming pregnant is the positive effect of folic acid. Folic acid, which is included in prenatal vitamins. The United States Preventative Services Task Force (USPSTF) recommends women who are planning a pregnancy to start taking a daily supplement of folic acid 0.4-0.8 ug per day, which is in all prenatal vitamins. Consuming adequate amounts of folic acid prior and during pregnancy reduces the risk of neural tube defects.
Vitamin D is another essential vitamin pregnant women should take. Vitamin D is needed for the absorption of calcium and phosphorus, which is needed for healthy development of bones and tissue. The recommended dose of Vitamin D for pregnant and women is 600 IU every day. Vitamin D can be difficult to obtain the right amount of vitamin D because it is not found in many foods and taking a prenatal vitamin can help meet this need.
Iron is a mineral that is often included in prenatal vitamins. During the second trimester there are many changes the body undergoes, and one is a physiological anemia. Iron in prenatal vitamins helps to improve and prevent anemia. Iron also helps with the development of the placenta and the baby’s growth.
Interestingly, one study found a negative effect of prenatal vitamins and rates of pregnancy among women who were undergoing fertility treatment. In a study by Campbell and colleagues, they noted that the rates of successful implantation with in vitro fertilization decreased significantly among women who took prenatal vitamins. Overall all pregnancy rates for women who took prenatal vitamins was 46%, compared to a pregnancy rate of 54% among women who did not take prenatal vitamins.
In all there is no clear or consistent evidence that supports the statement of prenatal vitamins improving fertility, however, there is clear and consistent evidence that supports the health benefits in having a healthier pregnancy and baby when taking prenatal vitamins.