By: Diana Barnes-Brown for Uterus1
Recently, a popular technique used for in-vitro fertilization (IVF) was connected to a higher risk of birth defects in pregnancies achieved with its help.
| Quick Facts About IVF and Infertility |
Infertility is characterized as the inability to conceive after one year of male-female sexual intercourse without contraception (or six months if the woman is over 35) or, in women, the inability to carry a pregnancy to live birth.
According to the ASRM, Infertility affects 6.1 million Americans, or 1 in 10 American women of reproductive age.
Approximately 44 percent of women who suffer from infertility seek medical assistance. Of those who do, approximately two-thirds are able to give birth.
More than 95 percent of people who undergo infertility treatment are treated with drug therapy or surgical procedures. Fewer than 5 percent need advanced reproductive technologies like in vitro fertilization (IVF).
The most recently available statistics indicate 64.2 percent of IVF pregnancies resulted in the birth of a single baby, 32 percent resulted in twins, 3.8 percent resulted in triplets or greater.
Assisted hatching, as the technique is called, relies on a miniscule laser or needle to puncture the thin membrane that surrounds “test tube” embryos thus increasing the chance of embryos’ implantation in the uterine wall, which is necessary for pregnancy to occur.
But research recently published by the Centers of Disease Control and Prevention (CDC) indicated that the use of assisted hatching increases the chance of monozygotic twinning, a process in which one fertilized embryo splits into two separate and viable cell masses which can then develop into twin babies. Monozygotic twins are also known as identical twins; they share the same genetic material and look exactly alike.
The risk of monozygotic, or identical, twins developing with birth defects is greater than that of fraternal twin pregnancies, where two eggs are fertilized separately and implant into the uterine wall individually creating twins who share no more genetic material than siblings born at separate times. This is because the embryo splits at a very early and fragile stage in monozygotic twinning, potentially placing delicate developing cells and genetic materials at risk of damage.
Apparently, for mothers whose pregnancies were achieved with the help of the assisted hatching technique, the chance of monozygotic twinning, and thus of birth defects, was far greater than for mothers who became pregnant by other means.
For mothers who had been impregnated using some eggs that had undergone assisted hatching, the likelihood of monozygotic twin formation was 1.7 times greater than those who had not. Mothers who had been impregnated using exclusively assisted hatching treated eggs were 4 times as likely to have monozygotic twins. The general likelihood of conceiving monozygotic twins is about 1 in 250, which means for IVF-plus-assisted hatching moms, the figure is closer to 1 in 125 or 1 in 60.
Other factors, such as the mothers’ age at the time of implantation, the number of previous attempts, and the number of embryos transferred into the womb, were found not to influence monozygotic twinning after IVF.