When is a pregnancy considered post-term?
Pregnancy from 37 to 41 weeks is considered normal in duration. A period of 41 weeks or more is considered a late full-term period, and 42 weeks or more is considered a post-term pregnancy. The accuracy of the calculation is crucial: the date of the last menstrual period may be incorrect if the cycle is irregular or late ovulation, so the main guideline is a first trimester ultrasound performed before 14 weeks. Often, an imaginary post-maturity turns out to be simply an error in determining the due date, and then no intervention is required.
- 37–41 weeks - full-term pregnancy
- 41 weeks or more - late term
- 42 weeks or more - post-term pregnancy
- The period is determined by ultrasound of the first trimester
- Imaginary postponement due to an error in the date
- The due date is a guideline, not an exact day.
Causes and risk factors
In most cases, no specific reason can be given. It has been noticed that post-term pregnancy occurs more often in first-time mothers, in women who themselves were born post-term, and in those who carried the pregnancy to term in a previous pregnancy, which indicates the role of heredity. Obesity and age increase the likelihood, as well as boy as the gender of the child. Rare causes are associated with characteristics of the fetus and placenta. The most common reason for formal post-term pregnancy remains an inaccurately determined gestational age.
- Inaccurately determined gestational age
- First birth
- Post-term pregnancy
- Hereditary predisposition
- Obesity
- Mother's age over 35 years
What does this threaten?
After 41 weeks, the placenta gradually loses its reserve, and the baby begins to receive less oxygen and nutrition. The amount of amniotic fluid decreases, which makes the umbilical cord more easily compressed. There is an increased likelihood of meconium leaking into the water and being inhaled by the baby at birth. Some children, on the contrary, continue to grow and become large, which complicates childbirth. For women, the risks of prolonged labor, trauma to the birth canal, and bleeding increase. All this explains why after 41 weeks observation rather than waiting is recommended.
- Decreased placental function
- Oligohydramnios and umbilical cord compression
- Meconium in amniotic fluid
- Large fetus and complications of childbirth
- Increased risk of caesarean section
- Birth canal injuries and bleeding
Observation
From the 41st week, the doctor prescribes regular monitoring of the child’s condition: CTG, ultrasound with measurement of the amount of amniotic fluid and Doppler measurements, usually at intervals of several days. At the same time, the maturity of the cervix is assessed, which determines the choice of method of induction of labor. A woman is advised to closely monitor movements and immediately report changes in them, as well as leakage of water or the appearance of discharge. Travel and prolonged absence of communication with the doctor during this period are undesirable.
- CTG every few days
- Ultrasound with assessment of the amount of water
- Doppler
- Assessment of cervical maturity
- Movement control
- Immediate response when status changes
What do they do next?
If labor does not begin on its own, doctors suggest induction - starting labor. The method depends on the maturity of the cervix: drugs are used to promote its maturation, mechanical methods, and when the cervix is ready, the amniotic sac is opened and intravenous administration of drugs that cause contractions. The timing of the induction offer is discussed individually, usually between 41 and 42 weeks. If there are signs of the baby's suffering, oligohydramnios, or the inability to induce labor, a caesarean section is performed. Traditional methods of stimulation have not proven effective and can be dangerous.
- Preparing the cervix for childbirth
- Induction of labor by drugs or mechanical methods
- Amniotomy for a mature cervix
- Caesarean section for complications
- Constant monitoring of the fetal heartbeat during labor
- Refusal to self-induce labor
