Stopping Birth Control Linked to Lower Vitamin D Levels

Birth control is a critical part of family planning for many women and taking contraceptives can lead to less painful periods, fewer migraines and headaches during your cycle and potentially reduce your risk for ovarian cancer.

But a new study indicates that birth control also may elevate vitamin D levels in the body, another positive side effect that ends once a woman stops taking this medication. 

The study, conducted by researchers at the U.S. National Institute of Environmental Health Sciences, involved more than 1,600 women ages 23 to 34 who lived in the Detroit area. Study participants who were part of a study of uterine fibroids provided blood samples and answered questionnaires that asked questions about their diets, supplement intake, behavior, contraceptive use, reproductive and medical history.

Researchers reviewed this data and found that women who took birth control patches, pills or rings had 20 percent higher levels of vitamin D. Women who stopped taking birth control had low-to-average vitamin D levels. Since UV rays also produce vitamin D, researchers accounted for this in the study and found that the amount of time participants spent outdoors did not factor into increased vitamin D levels. 

Vitamin D is a critical nutrient for the body. It exists in very few foods naturally, so many people get vitamin D through supplements and sun exposure. Vitamin D helps the stomach better absorb calcium and aids in bone growth. It also has been linked to a reduced risk of type 1 diabetes, breast, colon, prostate and lymphatic cancers (related to the immune system). 

Vitamin D deficiency is connected to an increased risk of osteoporosis and weak bones. People with limited sun exposure, kidney disease, liver conditions, malabsorption disorders such as Celiac disease and obesity typically are at risk for vitamin D deficiency. Research has shown that the rate of vitamin D deficiency in the U.S. nearly doubled over a 10-year period from 1994 to 2004 and that more than 40 percent of reproductive age women are vitamin D deficient. Though we don’t have extensive research on the link between vitamin D and reproduction, animal studies have shown that vitamin D deficiency may lead to underdevelopment of the uterus and impact egg production, which affects fertility. 

Researchers in the birth control study said supplement use was the best indicator of vitamin D levels, but more research needs to be done to better understand why using birth control leads to this increase. They say the study has clinical implications for counseling women who are trying to conceive. Testing their vitamin D levels could identify deficiencies that may affect their fertility, so it may be important for OB/GYNs to do these tests as part of an overall assessment of patients. Though blood test can help us gauge vitamin D levels, it’s also critical for patients to eat a healthy diet that includes foods like milk and cereals that are fortified with vitamin D. Supplements and increased sun exposure (with caution) also will help to increase these levels. If you have a muscle weakness, bone and muscle pain, fractures or difficulty walking, it might be a good idea to schedule a blood test with your doctor, especially if you are trying to get pregnant. Recognizing these symptoms, getting tested and finding out whether you have a  vitamin D deficiency could provide more clarity if you are facing fertility issues and enable us to develop a solid plan of action to help you get pregnant.