What Makes a Pregnancy High Risk? Factors Explained

A pregnancy is considered high risk when the mother, the baby, or both face a higher-than-average chance of complications. Risk factors fall into four broad groups: pre-existing maternal health conditions, complications that develop during pregnancy, a history of problems in prior pregnancies, and carrying twins or higher-order multiples.

"High risk" is a planning label, not a prediction. Most high-risk pregnancies end with a healthy parent and a healthy baby, especially when the risk is identified early and managed by the right team. Here is what falls into each category.

Maternal health conditions

Chronic conditions that predate pregnancy are the most common trigger. These include high blood pressure, pre-existing diabetes, obesity, thyroid disease, kidney disease, autoimmune conditions such as lupus, heart disease, and blood clotting disorders.

Mental health belongs on this list too. About 1 in 5 perinatal individuals experience a mood or anxiety disorder, and up to 75% go untreated.¹ Screening and behavioral health support should be part of any high-risk care plan.

Age also plays a role at both ends: pregnancies under 17 or over 35 carry added risk, though age alone is a gradient rather than a hard line.

Conditions that develop during pregnancy

Some pregnancies start routine and become high risk. Common examples include preeclampsia and gestational hypertension, gestational diabetes (which affects about 8% of U.S. pregnancies²), placenta previa and other placental problems, fetal growth restriction, birth defects found on ultrasound, and preterm labor.

This is why detailed anatomy scans and specialist ultrasound interpretation matter. Findings caught mid-pregnancy change the monitoring and delivery plan.

History from previous pregnancies

Obstetric history is one of the strongest predictors of future risk. A prior preterm birth, pregnancy loss, stillbirth, preeclampsia, or cesarean complication typically earns closer surveillance the next time, often starting in the first trimester.

Twins and multiples

Carrying more than one baby raises the likelihood of preterm birth, growth differences between babies, gestational diabetes, and preeclampsia. Most twin pregnancies, and essentially all triplet pregnancies, are managed as high risk from the start.

How high-risk status is documented

Clinicians document risk using ICD-10 diagnosis codes, including the O09 family, which covers supervision of high-risk pregnancy for reasons such as prior preterm labor or infertility treatment. Accurate documentation matters because it drives the monitoring schedule and keeps every clinician on the care team working from the same risk picture. (This is general information about documentation, not billing guidance.)

What changes when a pregnancy is high risk

Care usually means more frequent visits, additional ultrasounds and labs, and often a maternal-fetal medicine (MFM) specialist joining the team. Our overview of maternal-fetal medicine explains that role. Programs like nurse navigation, diabetes management, and dedicated high-risk pregnancy care keep the added complexity coordinated, including by telehealth when no specialist practices nearby.

Frequently asked questions

What does "high risk pregnancy" actually mean?

It means your care team has identified a factor that raises the chance of complications for you or your baby, so your pregnancy warrants closer monitoring and often specialist involvement. It does not mean something bad will happen. It is a signal to plan carefully, watch closely, and intervene early if needed.

What is the ICD-10 code for a high-risk pregnancy?

Clinicians use codes in the ICD-10 O09 category, "supervision of high-risk pregnancy," with subcodes for the specific reason, such as a history of preterm labor. Documentation like this communicates risk across the care team. The right code for any individual chart is a clinical documentation decision made by the treating clinician.

Can a high-risk pregnancy become low risk?

Sometimes. A concern flagged early, such as a suspicious ultrasound finding or borderline blood pressure, may resolve or prove benign on follow-up. Other factors, like a chronic condition or twins, remain for the duration. Either way, the label adjusts as new information comes in.

Sources

1. Policy Center for Maternal Mental Health / Maternal Mental Health Leadership Alliance. Prevalence and treatment of perinatal mood and anxiety disorders.
2. Centers for Disease Control and Prevention. Gestational diabetes affects about 8% of U.S. pregnancies.

If your organization cares for high-risk pregnancies without enough specialist coverage, we should talk.