Pregnancy Continuation Rates by Gestational Week
For healthy pregnant individuals with confirmed fetal viability, approximately 98.4% of pregnancies continue beyond 8 weeks, with miscarriage risk dropping to less than 1% after 9 weeks of gestation.
Early First Trimester (Weeks 6-8)
The highest attrition occurs in early pregnancy, with risk declining rapidly each week:
- Week 6: Miscarriage risk is approximately 9.4% after confirmed fetal cardiac activity 1
- Week 7: Risk drops to 4.2% 1
- Week 8: Risk further decreases to 1.5% 1
These rates apply specifically to asymptomatic women with confirmed fetal cardiac activity on ultrasound 1.
Late First Trimester (Weeks 9-13)
Pregnancy continuation improves substantially:
- Week 9: Miscarriage risk is only 0.5% 1
- Week 10: Risk remains low at 0.7% 1
- Weeks 11-13: Weekly miscarriage rates fall below 20 per 1,000 woman-weeks (approximately 2% per week) 2
The cumulative probability of miscarriage from weeks 5-20 ranges from 11-22% across populations, but this includes pregnancies without confirmed viability 2.
Second Trimester (Weeks 14-20)
Pregnancy loss becomes increasingly rare:
- Week 14 onward: Miscarriage rates drop below 10 per 1,000 woman-weeks (less than 1% per week) 2
- Weeks 14-20: Rates continue declining, falling well below 1% per week 2
The weekly miscarriage rate shows steady decline through week 20, with the most dramatic improvement occurring before 14 weeks 3.
Key Clinical Context
Important caveats for interpretation:
- These percentages represent continuation rates after confirmed fetal viability, not from conception 1
- Risk stratification matters: maternal age ≥30 years, underweight/obesity, alcohol consumption, and occupational factors (lifting >20 kg daily, night work) increase miscarriage risk 4
- The presence of fetal cardiac activity on ultrasound dramatically improves prognosis—women with confirmed heartbeat at 6-11 weeks have only 1.6% subsequent miscarriage risk 1
- Most miscarriages in women with early confirmed viability are diagnosed many weeks later; 45% are diagnosed in the second trimester 1
Population-level data shows:
Registry-identified miscarriage rates in developed countries have declined from 112 per 1,000 pregnancies (11.2%) in 1998 to 83 per 1,000 (8.3%) in 2016 5. However, these figures include all recognized pregnancies, not just those with confirmed viability 5.
The practical takeaway: After 8 weeks with confirmed fetal heartbeat, over 98% of pregnancies in healthy women continue to viability, and after 10 weeks, this exceeds 99% 1.