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Pregnancy Bliss | Reproductive Health Hub

Fetal well-being in Postmaturity

Are there any measures to check fetal wellbeing in the period leading to forty-two weeks of gestation?
Strictly speaking, there is no need to carry out any measures up to 42 weeks. This is because the baby is no more at risk in the forty-first or forty-second week compared to, let's say, the 37th, 38th, 39th or 40th week. If there was no reason to monitor in those weeks leading to the EDD, there should be no need to monitor in the two weeks after.

However, most obstetricians agree that some form of monitoring should be carried out: one, because there may be a risk factor that has been missed in the weeks leading to the EDD and two, to give peace of mind to all concerned, especially the expectant mother. When this monitoring should start depends on each obstetrician's opinion. Some start at forty weeks, most at forty-one weeks and a few will only monitor at about 10 days after the EDD (40w+10days) weeks.

Based on evidence accumulated over the years, in a low-risk pregnancy, all this monitoring is unlikely to influence any decision on the timing of delivery.

How is the fetal well-being assessed?
This will include monitoring the fetal heart activity using a cardiotocograph (CTG) and an ultrasound scan, which will be used to assess several factors, including amniotic fluid volume and fetal activity.

What is the role of Döppler ultrasound in assessing fetal well-being?
It has no role in low-risk pregnancy. Even in high-risk pregnancy, its usefulness remains limited and largely complementary.

After 42 weeks

What is to be done once the pregnancy has reached the 42 weeks mark?
Beyond this point, the pregnancy is prolonged. Most obstetricians will advise a plan for delivery by this stage. This could be induction of labour or caesarean section. The latter is used where induction of labour is considered risky or unsuitable. Ultimately, once she has been given all the information, the mother's wish is to be respected. A few mothers will still want to wait for spontaneous labour beyond 42 weeks.

Is there any risk to allowing pregnancy to continue beyond  42 weeks?
The post-term period (i.e. beyond 42 weeks) is not a fully understood area. Very few women are allowed to go beyond 42 weeks by more than a handful of days. In the few truly scientific observational studies of what happens in the 43rd week of pregnancy, there appears to be an increased risk of fetal loss. Some studies have claimed that by 43 weeks, fetal loss may go up threefold compared to term.

It is assumed that placental function deteriorates rapidly about this time. It can only be assumed that beyond 43 weeks, the risk will be higher. This is uncharted territory.

If the mother is keen to wait for spontaneous labour after 42 weeks, close fetal monitoring - probably every day or every other day – is likely be offered. This is reassuring but does not offer an absolute guarantee of continued fetal well-being. The truth is, even though CTG and ultrasound monitoring may be accurate for the here and now, in prolonged pregnancy its predictive value is reduced and things could be radically different within hours of a seemingly excellent score on the monitoring.
Expected date Term After 42 weeks Predisposing factors Fetal wellbeing Labour in postmaturity