NEW YORK (Reuters) - Nearly one in three women ages 18 to 24 have irregular menstrual cycles, which may mean pregnancies could be caught much later than the six-week abortion limit in Texas, a new study finds.
An analysis of menstruation data from nearly 270,000 U.S. women revealed that more than one in five women experience irregular periods. Percentages were higher among younger women, Hispanic women, and those with common health conditions, such as polycystic ovary syndrome and diabetes, researchers said in a report released by PNAS and scheduled for publication in that journal.
"Legislation that limits abortion access to the days before fetal cardiac activity may make abortion unequally accessible," said coauthor Jenna Nobles of the University of Wisconsin, Madison. "Because of differences in menstrual regularity, 'heartbeat bills' are likely to limit access to abortion for young people, Hispanic people, and people with common medical conditions for physiological reasons over which people have no control."
"Fertilization can occur as early as 12 days into the cycle, even for people with irregular periods," Nobles said in an email. "Since people with irregular periods can have cycles lasting 60 days or more, they could be many weeks into pregnancy before realizing they had missed their period."
Many people think bans like the ones in Texas give women a lot more time to more time to seek an abortion than they actually do, Nobles said.
"Calling fetal cardiac activity bans 'six-week' bans has been misinterpreted by policymakers as giving people six weeks to seek abortion," Nobles said. "This could not be further from the truth. A person with highly regular cycles who ovulates on day 14 has only a few days between the missed period and fetal cardiac activity. We show that menstrual irregularity is common and for people with irregular cycles, the window between the missed period and fetal cardiac activity may not exist at all."
To take a closer look at the prevalence of irregular periods, Nobles and her team turned to data from a mobile-device app that allows people to record menstrual cycles. In their analysis, the researchers used data on 1.6 million menstrual cycles reported by 267,209 U.S. women between 2014 and 2016.
Overall, 22% of women experienced cycle irregularity, which the researchers defined as consecutive cycles that differed by an average of seven-plus days. Women ages 18 to 24 were the most likely (31%) to experience irregular cycles, followed by those ages 25 to 29 (27%). Irregular cycles were also more likely in Hispanic women (30%) compared to other races/ethnicities.
Irregular cycles were also more likely in women with polycystic ovary syndrome (43%), type 2 diabetes (35%), obesity (32%), hormone irregularity (34%) and thyroid dysfunction (27%).
"Multiple factors — location, income, transportation — can limit abortion access for different groups of people," Nobles said. "We show that access to abortion may also be limited for physiological reasons over which people have no control."
The new study is "short and sweet and to the point," said Dr. Ashley Turner, an assistant professor of obstetrics and gynecology at Northwestern University's Feinberg School of Medicine.
"We all know that people reach out (for pregnancy testing) because they miss a period," Turner said. "For the most part, if they are not having regular periods they are not going to reach out as quickly."
The numbers in the study jibe with Dr. Turner's experience.
"I see people every day in a general gynecology practice who have irregular periods like that," she said. "Many are not tracking their periods or ovulation. They don't even think twice when they don't get a period that month, and maybe the next and the next."
The findings "lend more evidence to what we already know to be true," Turner said. "Many women don't find out they are pregnant until after six weeks."
SOURCE: https://bit.ly/2NziOqe PNAS, released December 27, 2021.
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