A late-term pregnancy is defined as 41 0/7 to 41 6/7 weeks' gestation; at 42 weeks' gestation, it becomes a postterm pregnancy. While the causes of postterm pregnancy are generally unknown, many supposed cases are likely due to a suboptimally dated gestational age. Risk factors may be maternal (e.g., age, previous postterm pregnancies, nulliparity) and fetal (e.g., male sex, disorders such as oligohydramnios). Patients with low-risk late-term pregnancies who have not had suboptimal gestational dating and who do not have indications for cesarean delivery or contraindications for induction of labor are usually offered the choice between expectant management with antepartum fetal surveillance and induction of labor. After 42 weeks' gestation, induction of labor is recommended regardless of cervical favorability in order to avoid associated complications. Membrane sweeping may be performed in well-dated pregnancies after 39 weeks' gestation to induce labor and prevent late-term or postterm pregnancy.
- Etiology: usually unknown 
- Risk factors for postterm pregnancy include:
This applies to patients without, , or .
Late-term pregnancy 
Begin by confirming whether the pregnancy was accurately calculated.for the
First-trimester prenatal ultrasound is preferred over other methods of determining . 
Suboptimally dated gestational age 
- Definition: a gestational age that was not confirmed or adjusted using ultrasound before 22 0/7 weeks gestation
- Perform induction of labor at 41 weeks' gestation (as determined by best clinical judgment).
Well-dated gestational age
Offer the following, using a shared decision-making approach:
- , if not previously done
- Choice of the following options:
|Management options for low-risk, well-dated late-term pregnancies |
|Induction of labor||Expectant management|
|Key points for patient counseling|
|Management steps|| |
Postterm pregnancy 
- Perform induction of labor by 42 0/6 weeks' gestation. 
- Induction unsuccessful: Perform C-section.
Postterm infant complications 
Increased birth weight and macrosomia, which can lead to birth trauma, e.g.:
- Low Apgar scores (i.e., ≤ 4 points) 
- Admission to the
- Cerebral palsy 
- Postmaturity syndrome: changes in appearance (i.e., weight loss, subcutaneous wasting, and dry, peeling skin) possibly caused by placental insufficiency and oligohydramnios 
Maternal complications 
- Associated with increased birth weight and fetal macrosomia:
- Infections: e.g., chorioamnionitis or endometritis 
We list the most important complications. The selection is not exhaustive.
Membrane sweeping 
- Definition: a procedure involving manually separating the amniotic membranes from the lower uterus wall during a pelvic examination
- Timing: may be performed at or after 39 0/7 weeks' gestation 
- Risks include:
- Contraindications: See “Contraindications for induction of labor.”