First-trimester ultrasound may lead to earlier abortion

Oct 30 2012

By Piriya Mahendra, medwireNews Reporter

Early diagnosis of structural fetal abnormalities by ultrasound during the first trimester would give women the option of undergoing abortion at a safer time in their pregnancy, research indicates.

Stephen Chasen (Cornell University, New York, USA) and team found that abortion was performed at a median gestational age of 18 weeks in 34 of 118 women who underwent early fetal evaluation (<14 weeks gestational age) and were diagnosed with structural fetal abnormalities.

In comparison, the median gestational age at which abortion was performed in the 28 women who were diagnosed with structural fetal abnormalities in the second trimester of pregnancy was 21 weeks. The intervals between prenatal diagnosis and abortion were similar in the two groups, the authors note.

Chasen et al believe that the benefit of diagnosing fetal abnormalities during the first trimester is that abortion is safer earlier than later in pregnancy, should women chose this option.

While 35.6% of women who had fetal abnormalities detected during an early fetal evaluation underwent an abortion by 16 weeks' gestation, none of the women who were diagnosed with fetal abnormalities during the second trimester had undergone an abortion by this time.

The median maternal age of the women who underwent early fetal evaluation was similar to that of women who underwent it in the second trimester. However, the median gestational age at the initial prenatal visit was earlier in women undergoing first-trimester ultrasound, at 8 weeks versus 13.5 weeks in women who did not.

In addition, the authors found that women who underwent early evaluation were significantly less likely to have Medicaid insurance and to be non-White than those who did not.

The retrospective review included 132 women who underwent abortion due to structural fetal abnormalities between 2004 and 2011 at a single institution.

"There are benefits of first-trimester ultrasound aside from earlier prenatal diagnosis, including precise gestational dating and very accurate assessment of amnionicity (ie, monoamniotic vs diamniotic) and chorionicity (ie, monochorionic vs dichorionic) in multiple pregnancies," write the authors in Contraception.

"Earlier diagnosis of fetal abnormalities, however, is very unlikely to change the prognosis of affected pregnancies in women who will not undergo abortion."

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