The Risks of Post-Term Pregnancy
A post-term pregnancy is one which continues beyond the 42nd week of pregnancy.
The vast majority of babies arrive between weeks 38 and 42. Around ten percent are born prematurely - or pre-term - and the same number (10 percent) are late, or post-term.
What are the risks of post-term babies?
Calculating the due date of a baby is not an exact science. The best we can do is estimate a delivery date based on a woman's usual monthly menstrual cycle. But of course not every woman is regular and that immediately puts any calculations at risk of being wrong!
So many pregnancies which mums or even GPs might think are post-term are actually nothing of the sort.
The actual number of post-term babies, based on ultrasound scans, is nearer the two percent mark.
What are the risks for late babies?
After 41 weeks the quantity of amniotic fluid inside the uterus may decrease severely. Which means the umbilical cord could get compressed during labour or delivery impeding the flow of oxygen to the baby.
Another risk is that meconium - baby's first bowel movement - may occur and could then seep into the amniotic fluid. A type of pneumonia can develop if an unborn baby inhales meconium into her lungs while in the uterus. This is why a baby's nose, mouth and back of her throat will be suctioned immediately after delivery.
On delivery of a post-term baby a tube may also be passed into the baby's windpipe to suction out any meconium before it can reach her lungs.
Another concern about post-term babies is their size. Babies who weigh more than 4,500 grams (9lbs 14oz) may struggle through the birth canal. This is why caesarean deliveries are more likely for post-term babies.
What happens if your baby goes post-term?
If your GP thinks your pregnancy has gone beyond 41 or 42 weeks they will go over earlier calculations carefully working out when the first movements and fetal heart sounds were monitored, the size of the baby, the height of mum's uterus (which is usually at the level of mum's naval at 20 weeks) and they will look back at clues from early ultrasound exams.
There are several tests which can confirm the condition of a post-term baby. An ultrasound scan will show if the amniotic fluid has depleted to a worryingly low level.
A decision will then be made as to whether the baby should be induced and whether a caesarean birth would be safest. Generally a pregnancy is not allowed to progress beyond 43 or 44 weeks.
Many doctors decide to wait to induce labour when the woman's cervix is softened and starting to dilate (ripe). A hormone gel can be placed in the cervix to speed this along.
Post-term babies often have long, thinner bodies and are sometimes born with long fingernails, a lot of hair, and wrinkled prune-like palms and soles from their extra time in the amniotic fluid.
The vast majority of babies arrive between weeks 38 and 42. Around ten percent are born prematurely - or pre-term - and the same number (10 percent) are late, or post-term.
What are the risks of post-term babies?
Calculating the due date of a baby is not an exact science. The best we can do is estimate a delivery date based on a woman's usual monthly menstrual cycle. But of course not every woman is regular and that immediately puts any calculations at risk of being wrong!
So many pregnancies which mums or even GPs might think are post-term are actually nothing of the sort.
The actual number of post-term babies, based on ultrasound scans, is nearer the two percent mark.
What are the risks for late babies?
After 41 weeks the quantity of amniotic fluid inside the uterus may decrease severely. Which means the umbilical cord could get compressed during labour or delivery impeding the flow of oxygen to the baby.
Another risk is that meconium - baby's first bowel movement - may occur and could then seep into the amniotic fluid. A type of pneumonia can develop if an unborn baby inhales meconium into her lungs while in the uterus. This is why a baby's nose, mouth and back of her throat will be suctioned immediately after delivery.
On delivery of a post-term baby a tube may also be passed into the baby's windpipe to suction out any meconium before it can reach her lungs.
Another concern about post-term babies is their size. Babies who weigh more than 4,500 grams (9lbs 14oz) may struggle through the birth canal. This is why caesarean deliveries are more likely for post-term babies.
What happens if your baby goes post-term?
If your GP thinks your pregnancy has gone beyond 41 or 42 weeks they will go over earlier calculations carefully working out when the first movements and fetal heart sounds were monitored, the size of the baby, the height of mum's uterus (which is usually at the level of mum's naval at 20 weeks) and they will look back at clues from early ultrasound exams.
There are several tests which can confirm the condition of a post-term baby. An ultrasound scan will show if the amniotic fluid has depleted to a worryingly low level.
A decision will then be made as to whether the baby should be induced and whether a caesarean birth would be safest. Generally a pregnancy is not allowed to progress beyond 43 or 44 weeks.
Many doctors decide to wait to induce labour when the woman's cervix is softened and starting to dilate (ripe). A hormone gel can be placed in the cervix to speed this along.
Post-term babies often have long, thinner bodies and are sometimes born with long fingernails, a lot of hair, and wrinkled prune-like palms and soles from their extra time in the amniotic fluid.
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