Estimate stillbirth risk based on gestational age, maternal factors, and known risk factors. Understand modifiable and non-modifiable risk contributors.
Stillbirth — the loss of a baby at 20 or more weeks of pregnancy — affects approximately 1 in 160 pregnancies in the United States. While this event is devastating, understanding the risk factors that contribute to stillbirth can empower families and healthcare providers to take preventive action where possible. This calculator summarizes common epidemiologic factors in a way that is easier to discuss than a raw risk estimate alone.
The Stillbirth Risk Assessment Calculator estimates risk based on well-established epidemiological risk factors including gestational age, maternal age, BMI, medical conditions, and lifestyle factors. It applies published odds ratios from large population studies to create a personalized risk profile.
This calculator is designed as an educational tool to help pregnant individuals understand their risk level, identify modifiable risk factors they can address, and have informed conversations with their healthcare providers about monitoring and prevention strategies. It is not a diagnostic tool and should never replace professional medical assessment. Check the example with realistic values before reporting.
Knowledge is power in pregnancy health. Understanding your personal risk profile helps you have informed conversations with your healthcare provider about appropriate monitoring, lifestyle modifications, and timing of delivery. This calculator also highlights modifiable risk factors — such as smoking and weight management — giving you actionable steps to reduce your risk.
Adjusted Risk = Baseline Rate (gestational age-specific) × Product of Odds Ratios for selected risk factors Baseline rates from population studies: ~3.0 per 1,000 at 28 weeks, varying by gestational age Odds Ratios from published meta-analyses of major risk factors
Result: 10.6 per 1,000 (1.06%)
With a baseline of 2.8 per 1,000 at 28 weeks, applying OR 1.8 for age ≥35 and OR 2.1 for obesity: 2.8 × 1.8 × 2.1 = 10.6 per 1,000.
Stillbirth risk factors fall into two categories: modifiable and non-modifiable. Non-modifiable factors include maternal age over 35, history of previous stillbirth, multiple gestation, and certain chronic medical conditions. Modifiable factors include smoking, obesity, substance use, and inadequate prenatal care.
The strongest evidence-based risk factor is a history of previous stillbirth, which increases the risk approximately 5-fold. This population benefits most from intensive surveillance, including serial ultrasound scans, non-stress tests, and considerations for earlier delivery.
Stillbirth risk varies significantly across pregnancy. The highest risk periods are before 28 weeks (primarily due to congenital anomalies and preterm placental failure) and after 40+6 weeks (due to post-maturity and placental insufficiency). The lowest risk period is 37-38 weeks.
This U-shaped pattern of risk by gestational age informs obstetric practice. High-risk pregnancies are often managed with planned delivery at 37-39 weeks to avoid the late-term risk increase while balancing neonatal outcomes.
For high-risk individuals, evidence-based strategies include early and comprehensive prenatal care with risk assessment at the first visit, serial growth ultrasounds to detect fetal growth restriction, low-dose aspirin for preeclampsia prevention, tight glycemic control for diabetic mothers, structured daily fetal movement counting, and individualized timing of delivery based on risk-benefit analysis.
In the U.S., about 1 in 160 pregnancies (6.2 per 1,000) result in stillbirth after 20 weeks. The rate is highest before 28 weeks and after 41 weeks, with a nadir around 37-38 weeks.
The strongest risk factors are previous stillbirth (OR 5.0), fetal growth restriction (OR 3.9), pre-existing diabetes (OR 2.9), and systemic lupus erythematosus (OR 3.0).
While not all stillbirths are preventable, addressing modifiable risk factors can reduce risk. Smoking cessation, managing chronic conditions, fetal kick counting, and appropriate antenatal surveillance are key prevention strategies.
The risk of stillbirth rises after 39 weeks due to placental aging and decreased reserve. This is why elective induction at 39 weeks is offered in some high-risk pregnancies.
This provides a population-level estimate using published odds ratios. Individual risk depends on many factors not captured here, including placental function, fetal anatomy, and genetic factors.
Decreased fetal movement can be an early warning sign of fetal compromise. Studies suggest that structured kick counting programs may reduce stillbirth rates by 30-50% in high-risk populations.