Baby Due Date Calculator, Twin Probability & Lifestyle Predictions

Planning for a baby involves practical questions: When will they arrive? What are the chances of twins? Our due date and lifestyle section answers these with data-driven estimates based on conception date, parental age, and health factors.

Due Date Calculation

Uses Naegele's rule: 280 days from last menstrual period (266 from conception). Only ~5% of babies arrive on their exact due date — most deliver between 37-42 weeks. The tool calculates the date and determines the baby's likely zodiac sign from projected birth month and day.

Twin Probability

Baseline fraternal twins: ~1.2%. Maternal age 35+: +0.8 percentage points. Family twin history: +3 points. Fertility treatment: +15 points. Identical twins remain ~0.4% regardless of factors. The tool adjusts probability based on your specific inputs.

Fertility, Life Expectancy & Metabolism

Female fertility peaks at ~95% (early 20s), declining to ~65% by 40. Male fertility stays above 88% until 45. Life expectancy baseline ~82 years, adjusted for genetic health risks and smoking. Metabolism speed and sleep chronotype (night owl vs. early bird) are also predicted from parental patterns, both having significant genetic components. Explore eye color predictions or check your own uniqueness.