Meconeum: When the baby opens his or her bowels during labor

When the fetus opens its bowels, passing the green stuff called meconeum, there is usually some concern as to whether this might be significant.

Passing meconeum before labor is uncommon but becomes more common, the further the pregnancy advances beyond 40 weeks. In fact, for those pregnancies reaching 42 weeks, roughly half of the babies will be found to have already passed meconeum when the ‘waters’ (membranes) are broken. This old meconeum tends to have a yellow tinge and any doctor or midwife will distinguish old from fresh meconeum. It is the fresh meconeum that is usually (but not always) significant.

Baby passing meconeum may indicate some degree of fetal distress. It is therefore regarded as a wise measure to do continuous CTG monitoring for a baby that has done this, particularly so if the meconeum is thick and fresh.

If the CTG is normal, the doctor may opt to do nothing other than continued monitoring and observation. If the CTG is equivocal, fetal blood sampling for analysis may be carried out.

When fetal blood sampling is not possible

If suspicious findings such as an abnormal CTG and passage of thick fresh meconeum cannot be verified, then a cesarean section becomes inevitable. This is not a situation in which one can afford to take. Better safe than sorry.

The special case of premature fetuses and distress in labor

Contrary to what one might fear, preterm babies are not more at risk of distress during labor.

However, small-for-dates babies whose growth during pregnancy has been sub-optimal are a different case. These babies are prone to fetal distress because of their inherent ‘weak’ state and the common problem of reduced amniotic fluid, and therefore the increased risk of cord compression.

Fetal distress and permanent brain damage risk

The oxygen deprivation needs to be severe and prolonged for lasting brain damage to occur. This is therefore a rare consequence of fetal distress in labor. Even for babies that are born floppy with a delayed cry and who end up in special care baby units for several days, the vast majority of them make a full recovery.

It is those unfortunate babies where the insult to the brain goes unsuspected and therefore unrecognized for a prolonged period in pregnancy where cerebral palsy may eventually result. This may also result in cases of quite acute episodes of conditions such as uterine rupture or severe placental abruption.

Next section: Cesarean section