Estimate when your baby is due based on the first day of your last menstrual period. This calculator uses Naegele's rule (adding 280 days to your LMP), adjusted for your cycle length if it differs from the standard 28 days. The result includes your estimated due date, conception date, current week of pregnancy, trimester timeline, and key NZ milestone dates including when to notify your employer about parental leave.
This calculator adds 280 days (40 weeks) to the first day of your last period (Naegele's rule), adjusted for your cycle length. Conception is estimated at approximately day 14 of a 28-day cycle. A dating ultrasound at 8 to 12 weeks provides a more accurate estimate. Only about 4 to 5% of babies arrive on their exact due date.
In New Zealand, eligible employees can take up to 26 weeks of primary carer leave. Paid parental leave (PPL) is currently up to 26 weeks, capped at $712.17 gross per week (from 1 July 2024). You must give your employer at least three months written notice before your intended leave start date. You are also entitled to 10 days of pregnancy-related leave for antenatal appointments (separate from sick leave and annual leave).
This calculator provides an estimate only and is not a substitute for medical advice. Your Lead Maternity Carer (LMC), midwife, or obstetrician will confirm your due date based on clinical assessment and ultrasound measurements. Only about 4 to 5% of babies are born on their estimated due date.
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