Pregnancy Complications and High-Risk Pregnancy

What makes a pregnancy high-risk

A pregnancy may be classed as high-risk because of factors present before pregnancy or problems that develop during it.

Pre-existing factors

• age under 17 or over 35
• pre-existing diabetes, high blood pressure, kidney disease, heart disease, epilepsy, thyroid disease or autoimmune conditions such as lupus
• obesity (BMI 30 or higher) or being underweight
• smoking, alcohol or drug use
• previous preeclampsia, preterm birth, stillbirth, cesarean delivery or recurrent miscarriage
• conception through IVF

Pregnancy-related factors

• twins or more (multiple pregnancy)
• complications such as those listed below

Common pregnancy complications

Gestational diabetes

Gestational diabetes is high blood sugar first found in pregnancy, affecting a significant minority of pregnancies in the US. It is screened for at 24 to 28 weeks with a glucose test, earlier in high-risk people. Untreated, it increases the risk of a large baby, birth injury, cesarean delivery and low blood sugar in the newborn. Diet, exercise and blood glucose monitoring control most cases. Some need insulin or metformin. It also raises the mother's later risk of type 2 diabetes, so testing after birth is recommended.

High blood pressure and preeclampsia

• Chronic hypertension: high blood pressure before pregnancy or before 20 weeks.
• Gestational hypertension: new high blood pressure after 20 weeks without organ involvement.
• Preeclampsia: high blood pressure after 20 weeks with protein in the urine or signs of organ strain.

Preeclampsia affects about 1 in 25 pregnancies in the US and can progress to eclampsia (seizures) or HELLP syndrome. Low-dose aspirin from 12 to 16 weeks reduces risk in high-risk people, as recommended by ACOG and the USPSTF. The only cure is delivery of the baby and placenta.

Anemia

Iron needs rise in pregnancy. Iron deficiency anemia causes tiredness and breathlessness and is checked by blood tests. Iron supplements correct it.

Hyperemesis gravidarum

Severe vomiting beyond normal morning sickness, causing dehydration and weight loss. See hyperemesis gravidarum.

Miscarriage and ectopic pregnancy

Miscarriage is pregnancy loss before 20 weeks, most often in the first trimester. Ectopic pregnancy is a pregnancy outside the womb and is a medical emergency if it ruptures.

Placenta problems

Preterm labor and premature rupture of membranes

Labor before 37 weeks affects about 1 in 10 US births. Risk factors include previous preterm birth, a short cervix, twins, infections and smoking. Treatments include progesterone for some high-risk people, steroids to mature the baby's lungs, and magnesium sulfate to protect the baby's brain. See preterm labor.

Fetal growth problems

Intrauterine growth restriction (a baby smaller than expected) and macrosomia (a large baby) are monitored with ultrasound and fundal height measurements.

Infections

Urinary tract infections, group B strep, and infections such as cytomegalovirus, toxoplasmosis, listeria and syphilis can affect the baby. Screening and food safety measures reduce risk.

Blood clots

Pregnancy and the 6 weeks after birth carry a higher risk of deep vein thrombosis and pulmonary embolism. Blood-thinning injections are used for people at high risk.

Mental health conditions

Perinatal depression and anxiety are among the most common complications of pregnancy and the year after birth. See postpartum depression.

How complications are detected

Routine prenatal care includes:

• blood pressure and urine checks at every visit
• blood tests for blood count, blood group and antibodies, and infections such as HIV, syphilis and hepatitis B
• first-trimester dating scan and screening tests for chromosomal conditions
• anatomy ultrasound at about 18 to 22 weeks
• glucose screening at 24 to 28 weeks
• group B strep swab at 36 to 37 weeks
• growth scans and fetal monitoring when risk is higher

Management of a high-risk pregnancy

• More frequent visits and scans, sometimes with a maternal-fetal medicine specialist
• Home monitoring of blood pressure or blood sugar
• Medicines, such as low-dose aspirin, insulin, antihypertensives safe in pregnancy, or blood thinners
• Planning delivery timing and place, for example delivery in a hospital with a neonatal intensive care unit
• Postpartum follow-up, because complications like preeclampsia and gestational diabetes signal higher long-term heart and diabetes risk

Reducing the risk

• a preconception visit to optimize long-term conditions and review medicines
• folic acid 400 micrograms daily from before conception through 12 weeks (higher doses for some)
• not smoking, no alcohol, and no recreational drugs
• reaching a healthy weight before pregnancy where possible
• recommended vaccines, including flu, Tdap and RSV at the right times
• attending all prenatal appointments and knowing the warning signs

For a quick guide to which symptoms are normal and which need a call, see pregnancy warning signs.

Frequently asked questions

What are the most common pregnancy complications?

The most common are gestational diabetes, high blood pressure and preeclampsia, anemia, severe nausea and vomiting, miscarriage, preterm labor, and placenta problems. Depression and anxiety during and after pregnancy are also very common.

What makes a pregnancy high-risk?

Age under 17 or over 35, pre-existing conditions such as diabetes, high blood pressure, heart or kidney disease, obesity, smoking, carrying twins, and previous complications such as preeclampsia or preterm birth. Problems that develop during pregnancy can also make it high-risk.

Can pregnancy complications be prevented?

Some can be reduced. Preconception care, folic acid, not smoking, a healthy weight, vaccines and low-dose aspirin for people at high risk of preeclampsia all lower risk. Many complications, such as most miscarriages, cannot be prevented, but early detection improves outcomes.

Do pregnancy complications affect future health?

Yes. Preeclampsia and gestational hypertension raise later risk of heart disease and stroke. Gestational diabetes raises the risk of type 2 diabetes. Regular blood pressure, glucose and cholesterol checks after pregnancy are recommended.

Will a complication in one pregnancy happen again?

Some complications are more likely to recur, including preeclampsia, preterm birth, gestational diabetes and placental abruption. Your care team can plan closer monitoring and preventive treatments, such as aspirin or progesterone, in your next pregnancy.