Saturday, December 22, 2012

IVF Method Linked to Size of Babies

Pregnant belly with stethoscope
A super-receptive uterus may be responsible for some recurrent miscarriages in women, research reported Aug. 24, 2012, suggests.
CREDIT:Pregnancy Photo via Shutterstock 

The way in which embryos are prepared during in vitro fertilization may influence the size of the baby that's born, a new study from Finland suggests. Embryos that spend long periods growing in culture (around five to six days) before being transferred to the mother’s womb are more likely to be born heavier than normal for their gestational age, compared to embryos that spend a shorter period in culture (two to three days), the study found. (Gestational age refers to how far along a pregnancy is.)

On the flip side, embryos that spend long periods in culture are less likely to be born small for their gestational age, the researchers said. Previous studies have shown babies born as a result of  IVF treatment are at an increased risk for preterm birth and low birth weight. Factors related to the pregnancy, or to the IVF technique itself, may be responsible for the association. Few studies have looked at the effect of culture time on the baby's birth weight, however. Still, additional, larger studies are needed to confirm the new findings, the researchers said.

In the study, researchers at the University of Helsinki analyzed information from 1,079 singleton babies (not twins) who were born after their mothers had undergone IVF. During IVF, eggs from the mother are fertilized in a laboratory, and allowed to grow in culture for about one to six days before they are transferred to the mother's uterus. Typically, embryos are transferred to the uterus after two to three days, according to the American Pregnancy Association. The Helsinki researchers determined the percentage of babies that were born at a normal weight; that were small for gestational age; or that were large for gestational age. Generally, 10 percent of babies are born small for gestational age, 10 percent are large for gestational age, and 80 percent are normal weight.

The average weight of babies in the study was about 7.7 pounds. Among embryos that were cultured for two to three days, about 10 percent were small for gestational age, and 10 percent were large for gestational age, as expected. But among those that spent five to six days in culture, close to 19 percent were large for gestational age, and 3 percent small for gestational age, the researchers said. Babies born small for gestational age are at increased risk for complications such as low blood sugar, and neurological disabilities. Later in life, babies that were small for their gestational age may be at increased risk for such chronic conditions as heart disease. Large-for-gestational-age babies may be heavier in childhood, and thus at increased risk for adult obesity, the researchers said.

The reason for the finding is not clear. It could be that certain stages of embryo development differ depending upon whether they take place in a laboratory or the womb, the researchers said. Large-for-gestational-age babies were also more likely to be born to mothers with high body mass index or to women who had previously given birth. The mother's age, cause of infertility or method of fertilization did not affect the results. The study was published online Dec. 11 in the journal Human Reproduction.

 Source: Live Science

1 comment:

  1. The Trouble With Getting Her Pregnant – IVF Tips
    Having trouble knocking her up? There can be many reasons for this, so don’t assign blame too quickly. If you have already made a gallant effort, it is probably time to go to the Obstetrician with your wife to get some answers. Chances are, the Obstetrician will in turn point you to a fertility center to determine exactly what is the problem. Our OB also suggested early on that we might want to freeze some of my wife’s eggs, in case we need them for fertility treatments. I have to say that, looking back, I am sorry that we didn’t do that at the time...