Girls born with a low birth weight may be at increased risk for fertility problems as adults, a new study from Sweden suggests.
Researchers looked at women who were seeking fertility treatment— whether it was because they were infertile or their partner was — and found women who were infertile themselves were about twice as likely to have been born with a low birth weight (less than 5.5 pounds) compared with those who were seeking fertility treatment because their husband/partner was infertile, or because the couple's infertility was unexplained.
The findings held true even after the researchers took into account factors that might affect women's fertility, including their body mass index (BMI) and whether they had given birth before. [5 Myths About Fertility Treatments]
However, because the study was small, and the first of its kind, more research is needed to confirm the link, the researchers said. And because the study was conducted in Sweden, it's not clear whether the results apply to women in other countries, they said.
An earlier study found that women who weighed less than 3.3 pounds at birth were less likely to give birth in their mid-20s than those with a higher birth weight, but that study did not look at whether the women had been diagnosed with fertility problems.
The new study analyzed information from more than 1,200 heterosexual women (most in their 20s and 30s) who sought fertility treatment along with their partners between 2005 and 2010.
About 38 percent of these couples had fertility problems attributed to the woman, about 27 percent had fertility problems attributed to the man, about 7 percent had fertility problems in both the man and the woman, and 28 percent had fertility problems that were unexplained.
About 3 percent of the women were born prematurely (before 37 weeks of pregnancy), and 3.6 percent weighed less than 5.5 pounds at birth.
The reason for the link between birth weight and fertility is not known, but one possibility is that growth restriction in the womb may affect the function of reproductive organs later in life, the researchers said. Previous studies have linked fetal growth restriction to a reduced ovulation rate.
The study, conducted by researchers at Linköping University, is published today (March 10) in the journal BMJ Open.