Complications of pregnancy are health problems that are related to or arise during pregnancy. Complications that occur primarily during childbirth are termed obstetric labor complications, and problems that occur primarily after childbirth are termed puerperal disorders. While some complications improve or are fully resolved after pregnancy, some may lead to lasting effects, morbidity, or in the most severe cases, maternal or fetal mortality.

Common complications of pregnancy include anemia, gestational diabetes, infections, gestational hypertension, and pre-eclampsia. Presence of these types of complications can have implications on monitoring lab work, imaging, and medical management during pregnancy.

Severe complications of pregnancy, childbirth, and the puerperium are present in 1.6% of mothers in the US, and in 1.5% of mothers in Canada. In the immediate postpartum period (puerperium), 87% to 94% of women report at least one health problem. Long-term health problems (persisting after six months postpartum) are reported by 31% of women.

In 2016, complications of pregnancy, childbirth, and the puerperium resulted in 230,600 deaths globally, down from 377,000 deaths in 1990. The most common causes of maternal mortality are maternal bleeding, postpartum infections including sepsis, hypertensive diseases of pregnancy, obstructed labor, and unsafe abortion.

Complications of pregnancy can sometimes arise from abnormally severe presentations of symptoms and discomforts of pregnancy, which usually do not significantly interfere with activities of daily living or pose any significant threat to the health of the birthing person or fetus. For example, morning sickness is a fairly common mild symptom of pregnancy that generally resolves in the second trimester, but hyperemesis gravidarum is a severe form of this symptom that sometimes requires medical intervention to prevent electrolyte imbalance from severe vomiting.

The following problems originate in the mother, however, they may have serious consequences for the fetus as well.

Gestational diabetes is when a woman, without a previous diagnosis of diabetes, develops high blood sugar levels during pregnancy. There are many non-modifiable and modifiable risk factors that lead to the development of this complication. Non-modifiable risk factors include a family history of diabetes, advanced maternal age, and ethnicity. Modifiable risk factors include maternal obesity. There is an elevated demand for insulin during pregnancy which leads to increased insulin production from pancreatic beta cells. The elevated demand results from increased maternal calorie intake, weight gain, and increased prolactin and growth hormone production. Gestational diabetes increases the risk for further maternal and fetal complications such as the development of pre-eclampsia, the need for cesarean delivery, preterm delivery, polyhydramnios, macrosomia, shoulder dystocia, fetal hypoglycemia, hyperbilirubinemia, and admission into the neonatal intensive care unit. The increased risk is correlated with how well the gestational diabetes is controlled during pregnancy, with poor control associated with worsened outcomes. A multidisciplinary approach is used to treat gestational diabetes. It involves monitoring blood-glucose levels, nutritional and dietary modifications, lifestyle changes such as increasing physical activity, maternal weight management, and medication such as insulin.

Hyperemesis gravidarum is the presence of severe and persistent vomiting, causing dehydration and weight loss. It is similar, although more severe than the common morning sickness. It is estimated to affect 0.3–3.6% of pregnant women and is the greatest contributor to hospitalizations under 20 weeks of gestation. Most often, nausea and vomiting symptoms during pregnancy are resolved in the first trimester; however, some continue to experience symptoms. Hyperemesis gravidarum is diagnosed by the following criteria: greater than 3 vomiting episodes per day, ketonuria, and weight loss of more than 3 kg or 5% of body weight. Several non-modifiable and modifiable risk factors predispose women to the development of this condition, such as a female fetus, psychiatric illness history, high or low BMI pre-pregnancy, young age, African American or Asian ethnicity, type I diabetes, multiple pregnancies, and a history of pregnancy affected by hyperemesis gravidarum. There are currently no known mechanisms for the cause of this condition. This complication can cause nutritional deficiency, low pregnancy weight gain, dehydration, and vitamin, electrolyte, and acid-based disturbances in the mother. It has been shown to cause low birth weight, small size for gestational age, preterm birth, and poor APGAR scores in the infant. Treatments for this condition focus on preventing harm to the fetus while improving symptoms and commonly include fluid replacement and consumption of small, frequent, bland meals. First-line treatments include ginger and acupuncture. Second-line treatments include vitamin B₆ +/- doxylamine, antihistamines, dopamine antagonists, and serotonin antagonists. Third-line treatments include corticosteroids, transdermal clonidine, and gabapentin. Treatments chosen are dependent on the severity of symptoms and response to therapies.