Among women undergoing assisted reproduction treatment (ART), those with vitamin D levels greater than 30ng/ml (or 75 nmol/L) were approximately 33% more likely to deliver a live baby, compared with women whose levels were deficient or insufficient, a systematic review and meta-analysis suggests.
A similar result was seen when the researchers looked at the results of pregnancy tests and clinical pregnancies (where a fetal heartbeat could be detected). When compared with women who had deficient or insufficient concentrations of vitamin D, women who had sufficient vitamin D were 34% more likely to have a positive pregnancy test and 46% more likely to achieve a clinical pregnancy.
What is also interesting is that other studies have shown that there are higher conception rates in summer and autumn when women might be expected to have more vitamin D due to exposure to summer sunshine. Foods such as oily fish, red meat, liver and egg yolks also provide vitamin D, as well as vitamin D supplements.
However, Vitamin D supplements must be taken with a meal. It is a fat-soluble vitamin and needs fat to be properly absorbed. Therefore taking Vitamin D with just a cup of coffee in the morning will have little effect on vitamin D levels as it is not being properly absorbed. Taking 2000IU of Vitamin D, ideally with a Vitamin K, per day from September until April is a good way to keep Vitamin D levels adequate. Of course in the summer months getting at least 20 minutes per day of direct overhead sunlight on the skin with no sunscreen is the best way to maintain adequate levels.