BALTIMORE — The increase in pregnancy and prenatal complications seen in women who undergo fertility treatments is likely related to maternal issues, not fertility drugs or assisted reproductive technology, according to a new study.
"Our findings suggest that factors inherent in the woman, rather than those attributable to infertility treatments, may explain the lower birth weight and shorter gestation associated with assisted reproductive technology," said Barbara Luke, ScD, from Michigan State University in East Lansing, who works with the Society of Assisted Reproductive Technology.
The study findings "provide a lot of reassurance that the kinds of treatment that some couples need to conceive, including in vitro fertilization, are not risky," said James Toner, MD, who is president of the society.
"The outcomes that infertile couples experience are pretty much the same, whether or not they need IVF treatment or get pregnant by some other method. The couples may themselves be a little different than couples whose fertility is easy, but the IVF treatment per se is not significantly increasing the risk of bad outcomes to the mother or the offspring," he explained during a news conference here at the American Society for Reproductive Medicine 2015 Annual Meeting.
In the population-based study, data on IVF and assisted reproductive technology from the Society of Assisted Reproductive Technology Clinical Outcomes Reporting System were linked to birth certificates to identify siblings of babies conceived with IVF and assisted reproductive technology in 12 states.
A total of 7810 pairs of siblings were identified.
The outcomes that infertile couples experience are pretty much the same, whether or not they need IVF treatment.
After adjustment for maternal age, weight, weight gain, parity, and sex of the infant, there were only minor differences in birth weight and length of gestation between spontaneously conceived children and their siblings conceived after fertility treatment.
Regardless of birth order, gestation was a day or a day and a half longer for spontaneously conceived children than for children conceived with fertility treatments, but the difference was not significant.
First-born children conceived with fertility treatments weighed slightly less than their spontaneously conceived siblings (3288 vs 3425 g), whereas second-born children conceived with fertility treatments were slightly heavier than their spontaneously conceived first-born siblings (3352 vs 3306 g).
"Looking within families is actually a more useful way to study assisted reproductive technology and other methods of conception, including spontaneous, because these children share a number of genetic, environmental, and social factors that you cannot necessarily control for when comparing children in the general population," Dr Luke pointed out.
In another population-based study presented at the meeting, Dr Luke reported on 470,000 pregnancies in fertile, subfertile, and infertile women in Massachusetts. Subfertile women were classified as women did not use assisted reproductive technology, but had some indicators of fertility problems.
That study linked data on IVF and assisted reproductive technology from the state databank to outcome, birth, death, cancer, and hospital discharge registries from 2004 to 2010.
Subfertile women and women who conceived with assisted reproductive technology had a slightly higher risk for gestational diabetes and pregnancy hypertension than fertile women.
In addition, women in the subfertile and assisted reproductive technology groups "had roughly a twofold increased risk of incompetent cervix, a 50% increased risk of prenatal hospitalization, more placental complications, and were more likely to have a primary cesarean section," she reported.
Table. Complications in Women by Study Group
| Complication | Fertile, % | Subfertile, % | Assisted Reproductive Technology, % |
| Gestational diabetes | 5.7 | 8.8 | 8.9 |
| Pregnancy hypertension | 8.7 | 11.8 | 16.1 |
| Incompetent cervix | 0.5 | 1.8 | 2.8 |
| Prenatal hospitalization | 4.2 | 5.4 | 8.4 |
| Prenatal bleeding | 0.6 | 1.1 | 2.7 |
| Placental complications | 1.7 | 3.0 | 5.2 |
| Primary cesarean delivery | 18.5 | 24.2 | 41.2 |
"Even in the subfertile women who did not receive assisted reproductive technology, there is an increased risk for prenatal complications and pregnancy complications, which helps us understand that it might not be related to the therapy itself, but to the factors inherent in the woman," Dr Luke concluded.
Dr Luke and Dr Toner have disclosed no relevant financial relationships.
American Society for Reproductive Medicine (ASRM) 2015 Annual Meeting: Abstract O-241, presented October 21, 2015; Abstract O-37, presented October 19, 2015.