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Sunlight exposure linked to improved fertility outcomes, study finds

Red sunglasses in the sand
A recent study suggests that moderate exposure to solar radiation during autumn and spring may improve ovarian reserve in women ages 30–40. Maria Altynbaeva/Stocksy
  •  Results from a recent study suggest that moderate exposure to solar radiation during autumn and spring may help improve ovarian reserve in women ages 30–40.
  • It’s too soon to determine the effects of solar radiation on fertility outcomes, particularly in younger age groups.
  • Research is ongoing about which factors affect female fertility and how women can modify these factors.

Many people face fertility challenges, particularly those who are over 35.

Researchers are exploring various potential causes of infertility, such as environmental factors, and whether modifying these factors could have any affect on fertility outcomes.

A recent study published in Steroids examined how exposure to solar radiation influences female fertility. Researchers examined levels of a specific hormone called anti-Müllerian hormone (AMH) and how levels of this hormone varied during different times of the year.

The results were significant for women over 30 who experienced higher levels of AMH in the spring and autumn when there were moderate levels of solar radiation intensity.

However, researchers did not observe this effect in women under 30, indicating that solar radiation may affect female fertility more with age. More research is required to understand these factors and the potential clinical implications. 

Sun exposure boosts female fertility

Researchers looked at how sun exposure influenced fertility among women of younger and older maternal age. This study was conducted in Israel and included 2,235 women mainly between 20 and 40 years old.

Researchers wanted to better understand the relationship between solar radiation exposure and anti-Müllerian hormone (AMH), an indicator of female fertility.

“When evaluating the fertility status of a patient, often, an anti mullerian hormone level is obtained. This level correlates to ovarian reserve. Studies have revealed that AMH declines with age, and therefore also does fertility,” non-study author Dr. Kelli V. Burroughs, a national media women’s health medical expert and department chair of OB-GYN at Memorial Hermann Sugar Land in Texas, explained to Medical News Today.

However, researchers of the current study note that AMH doesn’t necessarily reflect the quality of oocytes. 

The study authors looked at participant data for 4 years. Researchers measured solar radiation in the central district of Israel using data from the Israeli Meteorological Service website. 

Researchers found that AMH levels declined with age, so they divided participants into two groups: aged 20-29 years and 30-40 years. For women in the 20–29-year category, researchers did not find an association between AMH levels and the seasons or solar radiation intensity.

However, the results differed for women in the 30–40 year group. Researchers found that AMH levels increased for these women in the spring and autumn when there were moderate solar radiation intensity levels compared to the winter months when there were low solar radiation intensity levels.

The levels of AMH during months of moderate solar radiation exposure were overall higher than months that had high or low-intensity solar radiation levels. 

They also found that participants in the 30–40-year group who had AMH levels collected during the summer months had much higher AMH levels than participants who had AMH levels collected during the winter months. 

Researchers further divided participants into 30–35-year and 36-40-year groups. In the 30–35-year group, they did not find a significant correlation between solar radiation intensity or season and AMH levels. In the 36–40 group, they discovered that AMH levels were higher in the months of moderate solar intensity and higher in the summer compared to winter. 

The results indicate that exposure to moderate solar radiation may be helpful for women in their 30s who are trying to get pregnant. 

Dr. Burroughs noted the following: 

“This study is interesting because it suggests for women between ages 30-40 there is a possible seasonal influence on the AMH driven by the amount of sunlight or UV exposure. The mechanism behind the correlation of AMH and seasonal UV light exposure is unknown, but the study revealed higher levels of AMH with moderate UV exposure during spring and fall. It was also noted that low and high levels of UV exposure had the opposite effect on AMH levels.”

Factors that influence female fertility

Fertility is complex and affected by many components. Sometimes, it’s possible to modify certain factors Trusted Source National Institute of Child Health and Human Development Governmental authority Go to source  that may contribute to infertility.

For example, both obesity and being underweight can increase the risk of infertility. Smoking or heavy drinking can decrease fertility. Certain health conditions Trusted Source National Institute of Child Health and Human Development Governmental authority Go to source  can also impact female fertility, such as:

Non-study author Dr. Kecia Gaither, MPH, double board-certified OB-GYN and maternal-fetal medicine specialist and director of Perinatal Services/Maternal Fetal Medicine at NYC Health in New York, told MNT:

“There are many factors which impact fertility — drugs, stress, female factors (endometriosis, fibroids, polyps, hormonal imbalances, PCOS etc) [and] male factors (i.e., low sperm counts). It’s important to note the environmental aspect — (i.e., plain sunlight exposure) as a factor correlating with positive reproductive health [or] outcomes.”

One non-modifiable factor that affects female fertility is advanced maternal age as the chances of successful conception begin to decline after 35. 

Dr. Burroughs noted the following:

“More women than ever are delaying childbirth until their 30s and 40s for a variety of reasons including education, employment obligations, career-goals and increase[d] access to contraception. The result of delayed childbearing until the 3rd or 4th decade in life can impact fertility, because as a woman ages the ovarian reserve or number of eggs starts to decline. After the age of 35, a woman is considered advanced maternal age (AMA). This terminology reflects the correlation between age and declining fertility status.”

More research on the effects of sunlight on fertility needed

This study does have limitations. First, it doesn’t establish any causal relationship between the observed components.

Researchers also acknowledge that the lack of any significant association between AMH and seasons and participants between 20–29 years could be because of the difference in sample size between this group and the older group.  

Researchers also acknowledge that they did not analyze luteinizing hormone (LH) and follicular stimulating hormone (FSH) hormone levels in women aged 26–30, and this could have impacted their findings in this area. 

Researchers also note the possibility of confounding related to things like skin tone and cultural distinctions. Other factors like lifestyle and personal choices of participants could have also impacted the results. 

The research also focused on one area of the world, so the results could be different if conducted in other countries. Researchers did not take into account the origin of participants in their analysis. Finally, researchers did not have access to certain clinical information, like reproductive history. 

As research continues, study authors note that the potential benefits should be balanced with the possible risks of sun exposure, such as cancer or skin damage. 

This article originally appeared on Medical News Today.

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