Pregnancy Due Date Calculator

from datetime import date, timedelta

def calculate_due_date(lmp: date) -> dict:
    """Calculate estimated due date using Naegele's rule (LMP + 280 days)."""
    due_date = lmp + timedelta(days=280)
    today = date.today()
    days_remaining = (due_date - today).days
    gestational_days = (today - lmp).days
    gestational_weeks = gestational_days // 7
    gestational_day_rem = gestational_days % 7
    return {
        "lmp": lmp.strftime("%Y-%m-%d"),
        "due_date": due_date.strftime("%Y-%m-%d"),
        "days_remaining": days_remaining,
        "gestational_age": f"{gestational_weeks}w {gestational_day_rem}d",
    }

# Example
lmp = date(2025, 1, 15)
result = calculate_due_date(lmp)
print(f"Last Menstrual Period : {result['lmp']}")
print(f"Estimated Due Date    : {result['due_date']}")
print(f"Days Remaining        : {result['days_remaining']}")
print(f"Gestational Age       : {result['gestational_age']}")