Due Date Calculator

Pregnancy due date calculation uses Naegele's rule, established in the 1800s and still the standard today. While not perfectly accurate, it provides a reliable estimate for most pregnancies. **Naegele's Rule**: Estimated Due Date (EDD) = LMP + 280 days Or equivalently: EDD = LMP - 3 months + 7 days + 1 year Where LMP = First day of last menstrual period **Why 280 Days?** - 40 weeks = 280 days from LMP - Conception typically occurs ~14 days after LMP (during ovulation) - So actual gestational age is ~38 weeks (266 days) - The 'extra' 14 days account for the 2 weeks before conception **Pregnancy Timing**: | Weeks (from LMP) | Stage | What's Happening | |------------------|-------|-------------------| | 1-2 | Pre-conception | Egg developing | | 3 | Conception | Fertilization | | 4 | Implantation | Embryo attaches | | 4-5 | Missed period | Most positive tests | | 6-8 | First ultrasound | Heartbeat detected | | 12-13 | First trimester ends | Lower miscarriage risk | | 16-20 | Quickening | First baby movements | | 18-22 | Anatomy scan | Detailed ultrasound | | 24 | Viability | Baby could survive outside | | 24-28 | Glucose test | Check for gestational diabetes | | 28 | Third trimester begins | Final development | | 32-37 | Lung development | Final preparations | | 37 | Full term begins | Could deliver any time | | 40 | Due date | Average delivery | | 41-42 | Late term | Induction common | **Trimesters**: - **First trimester**: 1-13 weeks (most miscarriages occur here) - **Second trimester**: 14-26 weeks (often the easiest) - **Third trimester**: 27-40 weeks (preparation for birth) **Estimated Due Date Accuracy**: - **Only 4-5%** of babies are born on their exact due date - **80%** are born within 2 weeks of due date - **90%** are born between 37-42 weeks Factors affecting accuracy: - Cycle length variations - Late ovulation - Implantation timing - First-time vs subsequent pregnancies **When to Adjust**: The due date is sometimes adjusted based on: - Early ultrasound (most accurate at 8-13 weeks) - Known conception date (IVF) - Significant cycle length variations **First Trimester Concerns**: - Miscarriage risk (~10-20% of known pregnancies) - Severe morning sickness (hyperemesis gravidarum) - Fatigue and breast tenderness - Need for prenatal vitamins (especially folic acid) **Second Trimester Milestones**: - Energy returns - Showing physically - Feel baby move (quickening) - Anatomy scan reveals baby's sex - Lower risk period **Third Trimester Concerns**: - Glucose test for gestational diabetes - Group B strep test - Hospital tour and birth plan - Final ultrasound - Watching for preterm labor signs **Important Pregnancy Tests**: - **Beta-hCG**: Confirms pregnancy (4 weeks) - **NIPT (genetic)**: Down syndrome screening (10+ weeks) - **Anatomy scan**: Detailed ultrasound (18-22 weeks) - **Glucose tolerance test**: Diabetes screening (24-28 weeks) - **Group B strep**: Bacterial test (35-37 weeks) **Signs of Labor**: - Regular contractions (5 min apart for 1 hour) - Water breaking (clear amniotic fluid) - Bloody show (loss of mucus plug) - Severe back pain - Pelvic pressure **Average Pregnancy Statistics**: - **Total weight gain**: 25-35 lbs - **Days of nausea**: 60+ for many - **Hours of labor (first baby)**: 12-24 - **Postpartum recovery**: 6 weeks - **First-time parents lose**: ~700 hours of sleep in first year **Multiple Pregnancies**: - **Twins**: ~37 weeks average delivery - **Triplets**: ~33 weeks average - **Quadruplets**: ~30 weeks average Multiple pregnancies typically deliver earlier and require closer monitoring. **Late Pregnancy**: If you go past 41 weeks, doctors typically recommend: - Increased monitoring - Stress tests for baby - Induction at 41-42 weeks (varies by hospital) Going past 42 weeks is associated with increased risks. **When to Call the Doctor**: - Severe abdominal pain - Heavy vaginal bleeding - Severe headaches with vision changes - Signs of preterm labor before 37 weeks - Reduced baby movement after 28 weeks - Sudden severe swelling - Persistent vomiting