High levels of daily psychological stress are linked to lower estradiol levels in young women, according to a recent study published in Adaptive Human Behavior and Physiology (March 2015). The study is the first to provide evidence of the relationship between psychological stress and ovarian hormone production within the menstrual cycle.

Estradiol, a form of estrogen, is a female sex hormone produced by the ovaries that is especially important for maintaining the eggs inside a female’s ovaries.

There is limited research understanding the negative effects of psychological stress on ovarian hormone production, as well as the implications this has for fertility. However, a wide range of evidence suggests that the two factors are strongly connected. For example: psychological treatments aimed at reducing stress have been linked to faster times for conceiving in infertility patients; elevated cortisol (a physiological sign of stress) has been associated with early pregnancy loss; and higher adrenaline and noradrenaline levels (also related to stress) have been associated with lower success rates during in-vitro fertilization (IVF) treatment.

The study, by James Roney (University of California) and Zachary Simmons (University of Portland), assessed whether estradiol levels were lower on days with higher self-perceived stress than on days with lower stress within the same menstrual cycles. For the study, 36 young women provided daily saliva samples and also completed a daily survey in which they indicated self-perceived levels of stress.

The results revealed that days with higher stress ratings were characterized by lower levels of estradiol in the women’s saliva. The effect was still seen after other variables were accounted for, such as food intake, cold symptoms, exercise duration, and hours of sleep.

Despite being a correlational study, which usually limits the ability to establish cause and effect, the authors argued that there was no evidence that the higher estradiol levels caused participants to perceive events as less stressful. This being because both: high estradiol regions of the cycle were not associated with lower stress ratings; and the negative association between stress and estradiol was still present even after the region of the cycle was taken into consideration.

Therefore, the study appears to provide the first evidence of psychological stress causing a reduction in estradiol levels. The authors suggested that this effect could be part of an adaptive mechanism designed to temporarily inhibit reproduction when facing difficult circumstances.