Many women struggle to conceive and give birth to a baby, a situation that is known to cause distress and anxiety. But does it work the other way around, perhaps? Does stress cause infertility? Research over the past 20 years has attempted to determine whether levels of stress are associated with pregnancy rates, but the findings have been contradictory.
Now, in a study published today by The Endocrine Society, scientists have tested whether female rats that are exposed to a distressing scream sound have reduced fertility or diminished ovarian reserve.
Ovarian reserve refers to the number and quality of ova (egg cells) that remain in a female mammal’s ovaries, and is thus a measure of potential reproductive success in future. Female mammals are born with a finite number of ova in their ovaries, and they cannot generate more during their lifetime. Diminished ovarian reserve is the loss of normal reproductive potential in the ovaries due to a lower count or quality of the remaining eggs.
The researchers exposed a small sample of female rats to a scream sound for a period of 3 weeks and then analyzed the effect of this stressor on the levels of sex hormones, the number and quality of remaining ova, and the ability to become pregnant and give birth to young after mating.
“We examined the effect of stress on ovarian reserve using a scream sound model in rats,” said Dr. Wenyan Xi. “We found that female rats exposed to the scream sound had diminished ovarian reserve and decreased fertility.”
The researchers found that rats exposed to the stressful sound had decreased levels of estrogen and anti-Müllerian hormone. Estrogen hormones are important in growth and reproductive development, and anti-Müllerian hormone, produced by the ovaries, helps form the reproductive organs. These female rats also had ova in their ovaries that were less numerous and of a lower quality, resulting in smaller litters of offspring.
“Based on these findings, we suggest stress may be associated with diminished ovarian reserve,” said Dr. Xi. “It is important to determine an association between chronic stress and ovarian reserve because doing so may expand our appreciation of the limitations of current clinical interventions and provide valuable insight into the cause of diminished ovarian reserve.”
The study is published in the journal Endocrinology.