High-risk pregnancies are more likely in women who have difficulty getting pregnant, with or without help from hi-tech fertility treatments, new research finds.

The risks should be considered during pregnancy care of “subfertile” women and when analyzing the potential hazards of fertility-assisting technologies, Australian researchers conclude in a report published in the journal Fertility and Sterility.

Earlier studies had shown that women who conceived using in vitro fertilization and other fertility treatments had a higher risk of complications during pregnancy. What was less clear, note Alice Jaques, of the Murdoch Childrens Research Institute, and colleagues from other institutions in Australia, was whether the complications were linked to the technology used or to the mother’s underlying health issues.

They analyzed the pregnancies of 2171 subfertile women who sought fertility treatments between 1991 and 2001 but went on to become pregnant and give birth without using “assisted reproductive technologies.” Their pregnancies were compared to a randomly selected group of 4363 women who gave birth from the general population.

Compared to the control group, subfertile women were more likely to have pregnancy complications. For example, about 8 percent of these women had high blood pressure or pre-eclampsia - a potentially dangerous condition, marked by high blood pressure and protein in the urine, that develops in the second or third trimester - compared to about 5 percent of those in the general population. About 35 percent of the subfertile women required cesarean sections, compared to 23 percent in the general population.

Other increased risks included premature birth and low birth weight. While rare - 1.3 percent in the subfertile group, compared with 0.7 percent in the general population - infant mortality was also more common.

After taking into account other risk factors for premature delivery, including previous abortions, previous pregnancies and live births, and whether the patient gave birth in a public or private hospital, the authors concluded that “subfertility in itself somehow is associated strongly” with very premature birth.

The study results, Jaques and her colleagues note, identify the problem but don’t explain why risks during the pregnancies of subfertile women are higher.

SOURCE:  Fertility and Sterility, online 8 April 2010.