Medically reviewed by: Dr. Salli Tazuke, a board-certified reproductive endocrinologist and infertility specialist at CCRM Fertility of San Francisco
Vitamin D is known for playing an integral role in bone development by helping your body absorb calcium, but did you know it can also impact your immune system, heart health, digestion, and even your fertility?
Here’s how vitamin D may affect your reproductive health and vitamin D supplementation guidelines to keep in mind if you’re trying to conceive now or in the near future.
What is vitamin D?
Vitamin D is a vitamin in the body that helps regulate calcium levels, which keeps your bones, teeth, muscles, and immune system strong. It’s often referred to as the “sunshine vitamin” since you produce vitamin D when your skin is exposed to sunlight, but vitamin D is also found in some foods as well as supplements.
Normal vitamin D levels
Typical levels of 25-hydroxy vitamin D, the main storage form of vitamin D, depend on age, and typically range from 25-100ng/ml for adults. About 35% of adults in the United States are deficient in vitamin D, and in a 2019 Reproductive Health study of 500 participants undergoing assisted reproductive technologies (ART) such as in vitro fertilization, only 16% of people had normal levels of vitamin D.
Vitamin D for female fertility
In addition to bone health, vitamin D plays an important role in female reproductive health and hormone production. Sufficient levels of vitamin D have been found to help regulate ovulation and to help prepare the endometrial lining for pregnancy.
A 2024 study found that good vitamin D levels are associated with:
- Improved fertility outcomes
- Higher conception rates
- Successful pregnancy development
Vitamin D status also appears to be especially important for individuals undergoing assisted reproduction. A 2022 study found that women who have adequate levels of vitamin D have more successful outcomes as well as better-quality embryos, highlighting its role in reproductive outcomes.
Vitamin D for pregnancy
It’s important to maintain normal levels of Vitamin D after conception too. Research from a 2022 study reported that women with low levels of vitamin D more often had the following conditions than women with normal vitamin D levels:
- High blood pressure in pregnancy
- Preeclampsia
- Gestational diabetes
Additionally, a 2025 study concludes that not having adequate levels of vitamin D in the first trimester of pregnancy is more likely to lead to preterm birth. Together, these findings emphasize the importance of sufficient vitamin D throughout pregnancy for both maternal and fetal health.
Vitamin D for male fertility
Vitamin D is important for male overall health, but it can also help maximize male fertility and increase testosterone levels. Research indicates that increasing vitamin D levels can boost testosterone in men, which is crucial for libido, the ability to have an erection, and sperm production.
Lower vitamin D levels in men were associated with poorer semen quality, especially when it comes to sperm motility, according to one 2019 study. Sperm motility is how well sperm can move and travel through the female reproductive tract; better motility means higher chance of the sperm reaching and fertilizing an egg.
Vitamin D dosage for fertility
30ng/ml is the optimal vitamin D blood level for those trying to conceive. If you don’t know your vitamin D level, a doctor can order a simple blood test called the 25-hydroxyvitamin D test.
The International Osteoporosis Foundation recommends that all adults supplement their vitamin D3, and adequate intake is 400 IU per daily. If you have deficient levels of vitamin D, you can take higher dosages of vitamin D3 based on these recommendations below:
- If your level is >30ng/ml: Take 400-800 IU daily
- If your level is between 20-30ng/ml: Take 1000 IU daily (available over the counter) and recheck level in 12 weeks
- If your level is less than or equal to 20ng/ml: Take 50,000 IU once a week for 8 weeks (prescribed by a physician), then take 2,000 IU daily (available over the counter) and recheck level in 12 weeks
- If your level is <10ng/ml: In addition to taking 50,000 IU once a week, you will also need to be seen by an endocrinologist for long-term follow up care
How to boost your vitamin D level
In addition to supplementation, you can boost your vitamin D naturally level by:
- Getting some sunshine: The sun is one of the best sources of vitamin D. Aim to get 5-30 minutes of sunlight twice a week on your skin, longer if you have darker skin. Don’t forget to apply sunscreen!
- Eating seafood and fatty fish: Fish, especially salmon, tuna, oysters, and mackerel, are high in vitamin D.
- Consuming other foods containing vitamin D: Foods that have naturally high levels of vitamin D or have been fortified with vitamin D include dairy and plant milk, orange juice, cereal, yogurt, and tofu.
The bottom line
Vitamin D is essential for fertility health, but many of us don’t have the levels we need to optimize reproductive potential. A reproductive endocrinologist can help you assess if you’re getting enough of this important vitamin while you’re trying to conceive and advise you on how to supplement to maximize your chances of success.
To get started with a fertility specialist and learn more about vitamin D and fertility, schedule an appointment with CCRM Fertility.
