Missed periods due to exercise could spell heart-related complications during pregnancy or later in life: researcher
GIllian Rutherford - 16 September 2024
Nicole Tegg
It’s well-known that young women who train in sports like running or gymnastics may stop getting their periods for three months or more. What these athletes may not realize is that it could harm their health later in life, according to a University of Alberta PhD candidate in nursing.
Nicole Tegg is hoping to learn more about the condition and help young women get the message that missed periods are a cause for concern. She’s recruiting 20- to 45-year-old female participants for a study looking at the link between exercise-induced interruptions to menstruation and later complications during pregnancy such as high blood pressure, gestational diabetes and premature birth. These cardiovascular-related pregnancy complications are, in turn, known signs of an increased lifetime risk for cardiovascular disease in the mother.
“You look at long-distance runners or gymnasts and you think, ‘You are the picture of health, you’re doing everything right to reach this peak level of fitness,’ but if they’re missing periods, it could actually be causing cardiovascular damage,” Tegg says.
Tegg’s previous research, a systematic review of studies from around the world, showed that physically active women who miss periods for three months or longer have cholesterol changes similar to those observed in postmenopausal women, including higher total cholesterol, low-density lipoprotein cholesterol and triglycerides. The women also show impaired vascular function. Conversely, they have low resting heart rates and blood pressure, usually considered signs of fitness.
“These findings suggest that the beneficial effects of exercise on the endothelium (inner layer of the blood vessels) may be lost in physically active women who are missing periods,” Tegg says. “It’s important to have the cause of missed periods identified and to restore menstruation, because estrogen is very important for our heart and bone health.”
It’s all about estrogen
Another recent review found that 40 to 56 per cent of women involved with “lean” sports such as cycling, triathlon and ballet reported secondary amenorrhea, which means missing menstruation for three months or longer. Tegg’s review found some women skipping their periods for up to five years. And it wasn’t only athletes training at the elite level, but also some recreational participants.
The problem is caused by not taking in as many calories as are burned during physical activity over a period of time.The effect is to interrupt the body’s production of the hormone that stimulates the ovaries to make estrogen, resulting in missed periods and estrogen deficiency. Excessive stress, hormonal dysfunction or an eating disorder can cause this as well. The threshold for this effect is different for each woman, but the treatment usually involves increasing calorie intake and decreasing training time.
Tegg will carry out a mixed-methods study, first collecting information about the periods and pregnancies of 400 women, then selecting a smaller sample for in-depth interviews to gather more qualitative information about their attitudes towards missed periods. Tegg has heard anecdotally that many young women don’t mind missing periods, so they don’t report it to their doctors or seek treatment.
Understanding that phenomenon should help her target future public health messaging to the demographic.
“I want to get their perceptions, whether they saw missing their periods as something positive or negative, and did they report it to a doctor?” Tegg explains, noting that along with the heart-related health issues that she is focused on, estrogen interruptions can affect bone density and could put women at higher risk for osteoporosis.
Connecting the dots
Tegg came late to university research but is highly decorated for her work. She holds the University of Alberta Graduate Recruitment Scholarship, University of Alberta Doctoral Entrance Scholarship, Alberta Graduate Excellence Scholarship, Alberta Strategy for Patient-Oriented Research (AbSPORU) Graduate Studentship, Dr. Shirley Stinson Scholarship in Nursing History and the Women & Children’s Health Research Institute (WCHRI) Graduate Studentship.
After high school Tegg worked as a hairstylist and in restaurants, enjoying meeting people and hearing their stories. A friend took nursing, so she applied too, and worked as an RN in hospital labour and delivery for three and a half years before returning for her master’s degree. Tegg is now in her second year of a three-year doctoral program, with the goal of continuing as a nursing researcher.
Tegg was introduced to women’s heart health as a research topic by her thesis supervisor, world-renowned expert Colleen Norris, professor and associate dean of research in nursing and Cavarzan Chair in Mature Women's Health Research, who taught Tegg an undergrad statistics course years ago.
Tegg volunteers with the Canadian Women’s Heart Health Alliance, a group that includes health professionals and women who have experienced cardiovascular disease.
“There were quite a few women that were saying, ‘I'm only in my 40s, I was a long-distance runner, I was really fit. It’s really confusing and unfair that I developed heart disease,’” Tegg says. “Many were also mentioning pregnancy complications. So it got me wondering.”
Tegg posits that the missed periods due to exercise are like an insult to the vascular system that is then compounded by pregnancy, known as a “natural stress test” because a woman’s blood volume doubles during pregnancy. Ultimately these stressors could lead to heart problems later in life for some.
She couldn’t find any studies on the topic when she searched the academic literature, so now she has set out to connect the dots herself.
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