A new study published in the journal JAMA Network Open shows that the number of children a woman has is significant for the risk of ovarian cancer.
The researchers analyzed data from more than two million South Korean women over the age of 40, born between the 1930s and the 1960s.
The information was obtained from the country’s national health registry.
Women with two or more children generally had around a 30 percent lower risk of the disease.
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However, the effect was most pronounced among the older generations. Among women born in the 1960s, it was less marked.
Fewer births today
South Korea has experienced a significant decline in fertility. In the 1970s, women had an average of more than four children, while in 2022 the figure was below one, according to the data cited.
Previous research, particularly from Western countries, has shown that early menstruation may slightly increase the risk, while multiple pregnancies may reduce it.
One possible explanation is that more pregnancies result in fewer ovulations over a lifetime, which may reduce strain on the ovaries.
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In the South Korean study, the onset of menstruation at age 12 or younger and a long reproductive period were associated with an increased risk.
Need for prevention
The study also found that oral contraceptives were associated with a lower risk before menopause.
After menopause, the association was less clear, and hormone therapy was linked to an increased risk.
Overall, the results suggest that the protective effect of multiple pregnancies may become less important in societies with low birth rates.
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The researchers therefore emphasize the need for prevention strategies that take changing childbirth patterns into account.
Sources: Medical Xpress, and JAMA Network Open.
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