Women experiencing high levels of stress between five and eight weeks of pregnancy may face an increased risk of miscarriage, according to a new study. This finding highlights the potential impact of emotional wellbeing on early pregnancy outcomes, an area of growing interest for both medical professionals and expectant parents.
The research, published in Human Reproduction, was led by Dr. Amelia Wesselink of Boston University School of Public Health. Dr. Wesselink and her team analyzed data from PRESTO (Pregnancy Study Online), an ongoing prospective study that began recruiting participants between 2013 and 2025. The study includes women aged 21 to 45 residing in the United States and Canada who are actively trying to conceive naturally.
A total of 8,319 women completed the Perceived Stress Scale (PSS-10) early in their pregnancies. For comparison, 11,189 women had completed the same scale during the preconception period, with assessments repeated every eight weeks. The PSS-10 is a validated tool used to objectively measure stress levels.
approximately 20% of pregnancies in the study ended in miscarriage, occurring on average around six weeks of gestation.
Stress Linked to Higher Miscarriage Rates
After accounting for factors such as age and weight, researchers found a strong association between high PSS-10 scores measured between five and eight weeks of pregnancy and an increased risk of miscarriage. A score between 10 and 14 (on a scale of 0 to 40) was linked to a 38% increase in the relative risk of miscarriage compared to a score below 10. When the score exceeded 25, the relative risk increased by 105%.
Analyzing the data by week, the association between high stress and miscarriage was observed between weeks four and eight, peaking at week seven. Importantly, the study found no link between preconception PSS-10 scores – in either women or their male partners – and miscarriage risk.
Researchers acknowledge the study’s design as a cohort study, but emphasize that the large sample size and the use of a validated stress assessment tool strengthen the findings. The authors suggest that interventions aimed at reducing stress in early pregnancy could potentially lower miscarriage rates, “but confirmation of our results by randomized studies is necessary.”
Hormonal Pathways May Explain the Connection
The study suggests a potential biological mechanism involving cortisol, often referred to as the “stress hormone.” Elevated cortisol levels, triggered by activation of the hypothalamic-pituitary-adrenal axis, may disrupt progesterone production. Another proposed mechanism involves a decrease in the secretion of human chorionic gonadotropin (hCG), a hormone crucial for embryo implantation in the uterine lining.
