A recent study published by The Journal of Maternal-Fetal & Neonatal Medicine suggests that low vitamin D status may result in suboptimal endometrial thickness, thereby negatively impacting pregnancy outcome after intracytoplasmic sperm injection (ICSI).
Infertility occurs when a couple is unable to achieve pregnancy after 12 months of unprotected attempts to conceive a child. Up to 15% of the world’s population struggles with infertility, with men and women found to be equal contributors.
Assisted reproductive technology (ART) involves the use of fertility medication, artificial insemination, in vitro fertilization and surrogacy to help couples achieve pregnancy. Although there are several methods available to improve conception, intrauterine insemination (IUI) and intracytoplasmic sperm injection (ICSI) are most commonly used. IUI involves the direct placement of the sperm in the uterus during ovulation, while ICSI enhances the fertilization phase of in vitro fertilization (IVF) by injecting a single sperm into a mature egg.
Kezia Emmeny-Smith, an Embryologist at the Coastal Fertility Medical Center, provided some insight on this topic. She stated that IUI is typically a couple’s first step in fertility treatment, if they meet the eligibility requirements, because this process is more affordable than ICSI. However, the exclusion criteria for IUI is more extensive than that of ICSI. As a result, IVF/ICSI is typically performed in about 80-90% of cases.
Research has shown that vitamin D may play an important role in both male and female fertility. Due to the presence of vitamin D receptors in the ovaries and uterus, as well as the testes and male reproductive tract, researchers hypothesize that vitamin D may act locally to regulate the function of these organs. As a result, vitamin D is slowly gaining recognition for its role in fertility among the medical community. Despite this interest, many physicians have yet to begin routinely testing vitamin D status in couples experiencing fertility issues. Furthermore, no research to date has directly evaluated the relationship between vitamin D status and pregnancy outcome in patients who underwent ICSI.
Therefore, a recent study aimed to determine if vitamin D status is related to ICSI outcome. A total of 252 couples who visited the Islamabad Clinic for Serving Infertile Couples for ICSI were included in the study. Females were between the ages of 18-35 and their male partners had a sperm count of > 0.5 million/ml with 10% normal sperm morphology. All participants had their vitamin D levels measured during their first visit to the clinic. The researchers evaluated three important outcomes: oocyte (immature cell in the ovary) parameters, endometrial thickness and clinical pregnancies. An endometrial thickness ranging from 7-14 mm is ideal from promoting a successful pregnancy.
Here is what the researchers found:
- Of the 252 females that completed the ICSI cycle, 42% became pregnant (n = 108).
- The mean vitamin D status was significantly higher in the pregnant group compared to the non-pregnant group (17.74 ng/ml vs 9 ng/ml, respectively; p = < 0.01).
- Vitamin D status was positively associated with both pregnancy (p = 0.001) and endometrial thickness (p < 0.01).
- Higher vitamin D levels was associated with a 21% increase odds of clinical pregnancy (p < 0.05).
The researchers concluded,
“Deficiency of 25-OHD in females hinders the accomplishment of optimal endometrial thickness required for implantation of embryo after ICSI.”
They went on to state,
“The improvement in vitamin D status can thus improve success results in assisted reproductive clinics.”
Although the researchers successfully confirmed their hypothesis, as always, it is important to note the study’s limitations. Due to the cross-sectional design, the study is unable to prove causation. Additionally, the relatively small sample size and single center origin decreases the strength of its findings. As a result, randomized controlled trials are needed to definitively determine whether vitamin D supplementation will increase the rate of clinical pregnancy in couples undergoing ICSI.
Sturges, M. & Cannell, JJ. Vitamin D status linked to pregnancy outcome after intracytoplasmic sperm injection. The Vitamin D Council Blog & Newsletter, 2016.