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HomeHealth articlesprolonged pregnancyWhat Is Prolonged Pregnancy?

Prolonged Pregnancy - Causes and Complications

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Prolonged pregnancy is a pregnancy that lasts even after 42 weeks of gestation in a woman. Also called post-term pregnancy or postdate pregnancy.

Medically reviewed by

Dr. Priyadarshini Tripathy

Published At December 1, 2022
Reviewed AtJuly 6, 2023


Prolonged pregnancies are primarily due to misdating. The incidence of prolonged pregnancies is five to ten percent. In order to calculate the correct gestation period, the last menstrual period and urinalysis in the first three-month period play a primary role because this is the most critical time to interpret the correct due date and estimate the 42 weeks of the gestation period.

Failing in the first and most crucial step causes misinterpretation of dates and complicates the process. Prolonged pregnancies are risky to both mother and child. Induction of labor at term prevents the risk to the fetus and decreases the mortality rate. But these procedures have their own merits and demerits.

  • Early Term: 37 to 38 weeks.

  • Full Term: 39 to 40 weeks.

  • Late Term: 41 weeks.

What Are the Causes of Prolonged Pregnancies?

  • The first and primary cause is incorrect dates due to prolonged pregnancy terms.

  • Hereditary - If there is a familial history of post-term pregnancy, then the chances of having prolonged pregnancies in future generations are high. It is one of the most important etiological factors that one must consider.

  • During the second pregnancy, the chances of having a prolonged pregnancy are high. The previous history of post-term pregnancy can also cause prolonged pregnancies in the subsequent pregnancy. It can also occur in women who have had two to three pregnancies.

  • Sedentary habits during pregnancy can also lead to post-term pregnancy.

  • Body mass index is also one of the reasons for post-term pregnancy. Obese women are primarily at higher risk of prolonged pregnancy due to their decreased metabolic rate compared to one who is thin and have a correct body mass index. This risk can be corrected by following a proper diet and easy-moderate exercise.

  • A baby with a severe congenital disability in which the baby is born without parts of the brain and skull can increase the chance of having prolonged pregnancy.

  • Also, the placenta factors are one of the critical factors for post-term pregnancies. Placental sulfate deficiency is an X-linked recessive disorder that stops labor pain, resulting in decreased estrogen levels and post-term pregnancy.

  • Fetal adrenal insufficiency and adrenal hypoplasia cause decreased production of steroid hormones, causing delayed pregnancies.

  • Placenta produces peptide corticotropin-releasing hormone that regulates the duration of gestation. Failure of this leads to prolonged pregnancy.

  • Pregnancy is also prolonged post-term if the fetus is male.

What Are the Complications Associated With Prolonged Pregnancy?

  • Infants delivered after 43 weeks of gestation have thick viscous meconium coating the skin.

  • Long thin appearance and crinkling (formation of wrinkles) on the hands of the infants.

  • Unusual long nails.

  • Peeling skin, patches.

  • Lung irritation.

  • Partial lung collapse and pulmonary hypertension caused due to meconium aspiration (respiratory distress in a newborn who breathed a dark green sterile fecal material called meconium into the lungs before or at the time of birth).

  • Increased hemoglobin concentration in the blood.

  • Neonatal convulsions; decreased level of oxygen in the tissues.

  • Yellowish discoloration of hair, nails, and body.

  • Overweight neonates of more than four lbs.

  • The overall growth of the fetus is also restricted.

  • Birth injury if the baby is large.

  • The baby may stop gaining weight or may lose weight.

During Pregnancy:-

  • Decreased placental function there, fetal hypoxia (fetus is deprived of an adequate supply of oxygen), and distress.

  • Oligohydramnios means reducing the amniotic fluid volume in the gestational period, which can lead to poor fetal outcomes.

During Labor:-

  • Meconium aspiration.

  • Risk of umbilical cord compression.

  • One or both the shoulders of the fetus get stuck in the mother's pelvis during labor and birth.

  • Hardening of skull tissues causes birth trauma.

  • There is difficult or obstructed labor, slow dilatation of the cervix, and decreased uterine contractions.

  • Long-duration labor pain.

Maternal Complications:-

  • Increased despair; associated with threats of induction.

  • Instrumental and cesarean delivery.

  • Endometritis, severe bleeding, and thromboembolic disease.

  • Abnormally slow or protracted labor.

  • They are associated with a vaginal tear.

  • Increased morbidity.

  • Forceps or vacuum-assisted birth of the baby.

  • Infection wound complications and bleeding after delivery.

What Is the Diagnosis?

The first crucial step is keeping a record of the dates.

  • Last menstrual period date and early ultrasound scanning.

  • Weight record; fetal heart rate; the feel of the head; cervical condition.

  • History of false pain and internal examination.

  • Should timely carry out investigations to assess fetal maturity.

  • Sonography (a noninvasive procedure) every trimester and also amniotic fluid volume.

  • Doppler Flow Studies: This procedure uses sound waves to measure blood flow. This test is widely used to study if the developing baby is growing normally.

  • Measure the size of the uterus at certain points in early pregnancy.

  • Check whether the heart rate of the fetus responds to activity.

  • Check the amount of amniotic fluid.

How to Manage Prolonged Pregnancy?

  • Once the 37-week gestation period is over, make timely appointments with the doctor and discuss the options, and contact them if the fluid is coming out or bleeding immediately.

  • Induction of labor at the due date by performing a cesarean section;

  • Membrane stripping is a trouble-free procedure that can be carried out by increasing the production of prostaglandins.

  • Acupuncture and breast stimulation are other methods to induce labor.

  • After 42 weeks of pregnancy, in case they want to prolong, fetal surveillance is done.

  • After all, if the cervix is favorable, proceed towards induction of labor procedures.

  • If the cervix is unfavorable, then inclination toward the cesarean section.

  • Also, labor induction is contra-indicated in one with a contracted pelvis, previous cesarean section history, active genital herpes infection, heart disease, pelvic tumor and the prolapsed umbilical cord (the umbilical cord falls in the vagina ahead of the fetus).


Prolonged pregnancy correlates with maternal, fetal, and infant complications. Ultrasound scanning and other procedures have minimized the errors which used to cause misinterpretation of the dates in the olden days. The latest medical technology has increased accuracy and decreased most risks and problems. The complications not only arise after 42 weeks of pregnancy, but they also occur even during gestation. So overall, the gestation period and everything starting with the first trimester, each detail must be carefully recorded and avoid further complications in the long run.

Labor induction after 41 weeks is healthy for both mother and child and reduces complications. In some cases, the baby born after 43 weeks is healthy, but this does not apply to all patients.

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Dr. Priyadarshini Tripathy
Dr. Priyadarshini Tripathy

Obstetrics and Gynecology


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