Researchers looked at 59 studies to understand if vitamin D levels affect pregnancy success in women with PCOS (a common hormone condition) who are trying to get pregnant using IVF treatment. The review found that women with higher vitamin D levels before starting IVF treatment generally had better results, including higher pregnancy and live birth rates. However, the studies showed mixed results, so scientists say we need more research to figure out exactly how much vitamin D helps and the best way to use it.

The Quick Take

  • What they studied: Whether having enough vitamin D in your body before starting IVF treatment helps women with PCOS get pregnant and have successful pregnancies.
  • Who participated: The review analyzed 59 different research studies published between 2014 and 2024 that looked at women with PCOS trying to get pregnant using IVF. The studies included women of different ages and backgrounds.
  • Key finding: Women who had adequate vitamin D levels before starting IVF treatment appeared to have better pregnancy success rates and better egg development compared to women with low vitamin D levels.
  • What it means for you: If you have PCOS and are considering IVF, checking your vitamin D levels before treatment may be worth discussing with your doctor. However, more research is needed to know exactly how much vitamin D helps and whether supplements should be part of your treatment plan.

The Research Details

This was a systematic review, which means researchers carefully searched through published scientific studies and analyzed them together to find patterns. The team looked at studies published over 10 years (2014-2024) that specifically studied women with PCOS undergoing IVF treatment. They only included studies that measured vitamin D levels before treatment started and tracked pregnancy outcomes like fertilization rates, implantation success, pregnancy achievement, and live births.

The researchers followed strict guidelines called PRISMA standards to make sure they did the review fairly and completely. They excluded studies about infertility in women without PCOS to keep the focus narrow and specific. By combining information from 59 different studies, they could see if there were consistent patterns across different research groups and populations.

This approach is important because individual studies sometimes show different results due to differences in how they were done or who participated. By looking at many studies together, researchers can see the bigger picture and understand whether vitamin D really matters for IVF success in PCOS patients. This type of review helps doctors make better recommendations based on the strongest available evidence.

This is a systematic review, which is a strong type of research that combines many studies. However, the quality depends on the studies included—some were better designed than others. The researchers found inconsistencies between studies, meaning not all studies showed the same results. This suggests we need more standardized research where scientists use the same methods and vitamin D measurements. The fact that they followed PRISMA guidelines shows they were careful and transparent in their process.

What the Results Show

The overall pattern across the 59 studies suggests that women with adequate vitamin D levels before starting IVF had better outcomes than women with low vitamin D. This included higher rates of successful pregnancies, more live births, and better responses from the ovaries during treatment.

Women with sufficient vitamin D appeared to have better egg quality and better success with the embryo implanting in the uterus. The studies also suggested that vitamin D may help with the hormone and inflammation issues that come with PCOS, which could explain why it helps with fertility.

However, the researchers found that different studies measured vitamin D differently and used different cutoff points for what counts as ‘adequate’ vitamin D. This variation made it harder to draw firm conclusions about exactly how much vitamin D is needed.

Beyond pregnancy rates, the studies looked at several other important measures. Better ovarian response (meaning more eggs developing) was associated with higher vitamin D levels. Some studies also found that vitamin D may help reduce the inflammation and insulin resistance that often come with PCOS. These secondary findings suggest vitamin D might work through multiple pathways to improve fertility.

This review builds on earlier research suggesting vitamin D is important for reproductive health. The findings align with previous studies showing vitamin D deficiency is common in women with PCOS and may worsen their fertility challenges. However, this review is more comprehensive than previous work, examining a larger body of recent research and specifically focusing on IVF outcomes rather than general fertility.

The main limitation is that the 59 studies included had different designs and methods. Some studies were small, others were larger. They measured vitamin D at different times and used different definitions of ’low’ versus ‘adequate’ levels. Some studies didn’t track all the same outcomes, making direct comparison difficult. The review couldn’t determine the exact vitamin D level that works best or the ideal timing for supplementation. Additionally, most studies were observational (watching what happens naturally) rather than randomized controlled trials (where researchers assign people to different groups), which means we can’t be completely sure vitamin D causes better outcomes versus just being associated with them.

The Bottom Line

If you have PCOS and are planning IVF treatment, ask your doctor to check your vitamin D level before starting. If your level is low, discuss whether vitamin D supplementation might help. The evidence suggests it may improve your chances, though it’s not a guarantee. Moderate confidence: The research shows a positive pattern, but more standardized studies are needed to make strong recommendations.

Women with PCOS who are considering or planning IVF treatment should pay attention to these findings. Women without PCOS or those pursuing other fertility treatments should not assume these results apply to them. If you have other health conditions or take medications, discuss vitamin D with your doctor before supplementing.

If you start vitamin D supplementation, it typically takes several weeks to months to build up adequate levels in your body. Most IVF cycles are planned weeks to months in advance, so there’s usually time to optimize vitamin D levels before treatment begins. Don’t expect immediate results—vitamin D works gradually to support your body’s systems.

Want to Apply This Research?

  • Track your vitamin D supplementation daily (dose and timing) and note your vitamin D blood test results before and during IVF treatment. Record the date you started supplementation and any changes in your treatment plan.
  • If your doctor recommends vitamin D supplementation, set a daily reminder to take your supplement at the same time each day (ideally with a meal containing fat for better absorption). Log your supplement intake in the app to maintain consistency.
  • Schedule vitamin D blood tests at key points: before starting supplementation, 8-12 weeks after starting, and before beginning IVF treatment. Track these results in the app alongside your IVF timeline to see if your levels improved and correlate with your treatment outcomes.

This review summarizes research findings and should not replace professional medical advice. Vitamin D supplementation decisions should be made with your doctor or fertility specialist, especially if you have PCOS or other health conditions. The evidence suggests vitamin D may help with IVF outcomes in PCOS patients, but it is not a guaranteed treatment and should be part of a comprehensive fertility plan. Always consult with your healthcare provider before starting any new supplements, as they can interact with medications or other treatments. This information is for educational purposes and does not constitute medical advice.