"Miracle Baby" Amillia Taylor

The survival of this tiny, premature baby, who was born in October but just this past week was able to go home with her parents, has been all over the news.  There seems to be a lot of confusion over exactly what Amillia's gestational age was at birth.  ABC News described her as "born at just 21 weeks and six days," but then asserted, "Amillia is perhaps one of the world's smallest surviving babies — although doctors say her age was determined by the day of conception (she was an IVF baby), rather than the conventional method of using the date of the mother's last menstrual period, making her actually two weeks older."

Newsweek also described her as a "21-week six-day old fetus," but added: "the language of pregnancy can be confusing. On her first pre­natal visit, Lievano [the obstetrician who delivered Amillia] said, the mother miscommunicated her dates. As a result, he thought the baby was two weeks older than she actually was."

The Miami Herald reported that Amillia was "born in October at a record-low 22 weeks, six days in the womb."

Why all the confusion about Amillia's gestational age?  "Gestational age" is typically defined as the amount of time a fetus spends in the uterus from fertilization (also referred to as conception) until birth.  However, in most pregnancies the exact date of fertilization cannot be determined.  Instead, by convention the "gestational age" is measured from the first day of the woman's last menstrual period.  A baby is considered to be full-term when born between 38 and 42 weeks' gestation.  Ovulation, however, generally does not occur until two weeks after a woman's menstrual period begins.  Accordingly, when we say a fetus's gestational age is 40 weeks, if measured based on the woman's menstrual period, that fetus probably in fact spent closer to 38 weeks in the womb.  Technological advances have made it possible to measure more precisely a fetus's gestational age in some circumstances:  in pregnancies resulting from in vitro fertilization, for example, the moment of conception is known; doctors can also use ultrasonographic measurements of fetal growth in order to estimate gestational age. 

Regardless of how Amillia's gestational age is measured, many are discussing how her survival at such a premature stage may affect the abortion debate.  More on that in the next post.