Babies conceived through fertility treatment may be somewhat smaller at birth than children conceived naturally, but is not yet clear whether this is due to therapy itself or underlying maternal infertility, according to a U.S. study.
A group of researchers looked at almost 2,000 women and found that babies born to those with fertility problems weighed just under 453 grams-a-half, according to results published in the journal Fertility & Sterility.
These children also were at greater risk of low birth weight, i.e., be below the 2.49 kilograms.
“But it’s hard to tell. Is it due to infertility or the technology used to treat it?” said Amber Cooper, assistant professor of obstetrics and gynecology at Washington University in St. Louis, who led the study.
Previous research has linked poor fetal growth and lower birth weight with increased risk of developing certain health problems in adulthood such as hypertension and heart disease.
Cooper’s team looked at the records of 461 women who came to the center with fertility problems for 10 years and finally had a baby.
More than half underwent in vitro fertilization (IVF), while 106 were treated with drugs and 104 eventually became pregnant on their own. The 1264 patients were compared with fertile women who gave birth during the same period.
In general, babies born to women with fertility problems were smaller. But there was no difference in birth weight between children of women who underwent IVF and those infertile ended up having a baby without medical help.
The gap was observed in the group of women who had been treated with fertility drugs, which stimulate ovulation. Their newborns were about 225 grams lighter than fertile mothers, a difference that Cooper described as small but still significant.
On the other hand, the increased risk of low birth weight baby was seen mainly in childbirth by IVF. 12 percent of these mothers had a low birth weight, compared with just fewer then 8 percent of mothers with no fertility problems.
“The results suggest that a large portion of this would be related to the underlying infertility,” said Cooper.
Drugs to treat infertility are often used in women whose condition is related to ovulation problems. For this study, almost half the group treated with medication.
Previous research also suggested that the more delayed a couple to conceive, the greater the chances of low birth weight baby, or other complications.
IVF is usually performed only after failing drugs or other less comprehensive.
However, the researchers of this study could not link the low birth weight with specific causes of infertility, and Cooper stressed that it is not excluded an effect of the technology.
Since about 2 percent of annual U.S. births are now attended by a fertility treatment, will be important to study the effects of therapy on long-term health, noted the author.