It really is difficult to find a lot of statistics on anencephaly. The following is the most reliable report I've been able to find.
Report about the birth and life of babies with anencephaly
by Monika Jaquier
When parents get the diagnosis of anencephaly for their unborn baby, they often get only a minimum of information about what is in store for them. Doctors generally cannot tell them much about how long the baby could be expected to live, as most physicians have seen only very few cases in their practice. There exists almost no published information regarding the spontaneous outcome of a pregnancy with a baby affected by anencephaly.
But parents have questions. They need to know as much as possible about their baby’s condition.
Is there a risk that the baby will die during the pregnancy, in his mother’s womb?
What are the chances that the baby will survive birth?
How long do babies with anencephaly survive after birth?
Are there any factors that can give the baby a better chance for surviving the birth?
To answer those questions and to help families preparing for their baby’s birth, questionnaires were sent to families who opted not to terminate the pregnancy. These families met through the website http://www.anencephalie-info.org .
Data regarding 303 babies was collected. All babies were diagnosed with anencephaly and were carried to term or until spontaneous premature birth.
The information gathered is surprising. The results may impart courage to affected families and allow obstetricians to offer better advice after the diagnosis. There is no doubt that anencephaly is always fatal, but the chances to be able to hold your baby alive in your arms are good.
Almost 40% of the babies were born prematurely (before 37 weeks of gestation) and 4% beyond term (after completing 42 weeks of gestation). Among those who were born at term, 2/3 of the mothers had the birth induced or had a planned c-section.
In 30% of the cases, too much amniotic fluid (polyhydramnios) did build up. This condition doubles the risk of a premature birth. Among those who had polyhydramnios, almost 60% of the babies were born before 37 weeks, against 30% among the unaffected pregnancies.
Other pregnancy complications were rarely recorded. Many mothers with previous pregnancies noted no subjective difference regarding general well-being between their pregnancies. Often fetal movements with the affected baby were more intensive than with a healthy baby.
In almost all cases, a vaginal delivery was possible without problems. Contrary to the belief that delivery may be prolonged due to the lack of cranium and smaller head, mothers with previous pregnancies noted no subjective difference regarding the length and intensity of labor. Of those who chose a vaginal birth, 42% had a spontaneous delivery.
Several mothers asked for a planned Caesarean section (c-section) with the aim of avoiding stillbirth. Another indication was a pregnancy with multiples, where everything was done to reduce the risk for the healthy twin / triplets.
The baby's life up to and after birth:
Contrary to common belief, only a small number of affected babies died in utero.
Here are the statistics:
7% died in utero
18% died during birth
26% lived between 1 and 60 minutes
27% lived between 1 and 24 hours
17% lived between 1 and 5 days
5% lived 6 or more days
Thus, of babies conceived with anencephaly, 75% survived the birth. Nevertheless, there were significant differences in survival rates as related to different birth methods.
In case of a planned c-section, only 4% died during birth (all those babies had additional malformations which increase mortality). Not only did more babies survive the birth, but they also lived longer. Of affected babies born by c-section, 53% died within 24 hours, 30% lived up to 5 days, and 13% lived longer than 6 days.
In case of vaginal birth, the risk of stillbirth following artificial rupture of the membranes is twice as high as if no intervention is done. When the amniotic bag was ruptured by the obstetrician or midwife, 37% of the babies died during birth against 18% when water broke naturally.
Pregnant women should draw their obstetrician’s attention to this fact in order to increase the chance of a live-birth.
The length of pregnancy is decisive as well. There is no significant difference between the rate of live-births of babies born before 37 weeks of gestation or thereafter. But premature babies have a lower life expectancy, as only 7% live longer than 24 hours as opposed to 32% of the babies born after 37 weeks.
There is a female preponderance between babies with anencephaly. The ratio of female to male was of 3 to 2.
For babies born at 40 weeks, the average weight is 2740grams (6.02 pounds).
Additional malformations were present in 9% of the babies. This may be an underestimate as it refers only to malformations seen at the ultrasound or after the baby’s birth such as Myelomeningocele, omphalocele, cleft lip, cleft palate, heart defects, malformed digits, and so on.
A positive family history for neural tube defects (i.e. anencephaly, spina bifida or myelomeningocele, closed spinal dysraphisms) was reported in 5% of the families.
Of the 9 mothers who had a homebirth, there were no complications and all the babies survived the birth.
The baby with anencephaly was one of a multiple pregnancy in 41 cases. Of these, 37 mothers were pregnant with twins and 4 with triplets.
Among all those families who opted for continuing the pregnancy rather than having an elective termination, not one family regretted their earlier decision to carry to term. Many wrote how important it has been for them to see and touch their baby, stillborn or live born, to give him or her a place in their family, and to conduct a burial.
I’m very grateful to the parents who have generously provided information; without their support, this report could not have been produced.
March 7, 2006
Correspondance to: Monika Jaquier
Read also: Jaquier M, Klein A, Boltshauser E., Spontaneous pregnancy outcome after prenatal diagnosis of anencephaly, BJOG 2006; 113:951-953