Pregnancy Due Date Calculator Canada 2026

An estimated due date (EDD) calculated from your last menstrual period assumes a 28-day cycle with ovulation on day 14 — accurate for many women but a general estimate. Early ultrasound dating (7–13 weeks) is more precise, typically within 3–5 days. Only approximately 5% of babies are born on their exact calculated due date. Most full-term deliveries occur within 2 weeks before or after — from 39 to 41 weeks. Babies born between 39 and 40 weeks and 6 days are considered full term; 37–38 weeks is early term; 41 weeks and beyond is late term. Think of your due date as the midpoint of a likely 4-week delivery window.

The most common method is Naegele's rule: add 7 days to the first day of your last menstrual period, then subtract 3 months (or equivalently add 9 months and 7 days). For a LMP of January 1, 2026: add 7 days = January 8; add 9 months = October 8, 2026. This gives a full 280-day (40-week) pregnancy counted from LMP. The reason pregnancy is counted from LMP rather than conception: LMP is a definite known date, while actual conception typically occurs approximately 14 days later and is much harder to pinpoint. Medical gestational age is always measured from LMP in standard obstetric practice.

Canada offers two EI maternity/parental leave options. Standard option: 15 weeks maternity leave (birth parent only) plus 40 weeks parental leave shared between parents, at 55% of insurable earnings (max insurable $68,900). Extended option: 15 weeks maternity leave plus 69 weeks parental leave shared, at 33% of insurable earnings. The federal government also provides a 5-week "use it or lose it" bonus for the second parent. Ontario provides an additional 16 weeks of unpaid pregnancy leave (for a total of 78 weeks of job protection) under the Employment Standards Act. Plan maternity leave finances early — EI payments typically begin approximately 2 weeks after application and involve a 1-week waiting period.

Gestational age (GA) is counted from the first day of the last menstrual period — the standard medical measurement. At 4 weeks gestational age, the embryo is actually only approximately 2 weeks old post-fertilisation. Embryonic age (also called fetal age or fertilisation age) counts from actual conception — approximately 2 weeks less than gestational age for regular 28-day cycles. Medical providers always use gestational age when discussing pregnancy milestones, ultrasound measurements, and due dates. When you read "your baby at 8 weeks," this means 8 weeks gestational age, or approximately 6 weeks since actual fertilisation. This is why early pregnancies count from the last period even before conception has occurred.

Many couples wait until after 12–14 weeks (the end of the first trimester) before announcing widely, because the risk of miscarriage drops substantially after week 12. The risk of miscarriage is approximately 10%–15% overall in clinically recognised pregnancies, but closer to 2%–3% after the first trimester heartbeat is confirmed. There is no medical requirement to wait — some parents announce much earlier, especially to close family and support people who would be part of any outcome. The decision is entirely personal. Early disclosure to your employer may be appropriate if your work involves physical risk or you need accommodations — Ontario employers must provide accommodation upon request during pregnancy.

OHIP covers standard prenatal care including all prenatal physician or midwife visits, routine prenatal blood work (blood type, CBC, infections screening, glucose tolerance test), standard ultrasounds (dating ultrasound at 7–12 weeks, anatomy scan at 18–20 weeks), and Group B Streptococcus screening at 35–37 weeks. The Prenatal Screening Ontario (PSO) program covers cell-free DNA (cfDNA) screening for chromosomal conditions for high-risk pregnancies and expanded non-invasive prenatal testing (NIPT) for eligible patients. Additional private testing (expanded NIPT panels, genetic carrier screening beyond covered tests) involves out-of-pocket costs ranging from $300–$800 depending on the panel selected.

Key tax considerations for expecting Canadian parents: (1) The Canada Child Benefit (CCB) begins the month after your baby is born — register with CRA immediately by registering the birth. A family with one child under 6 at $80,000 income receives approximately $5,765/year. (2) EI maternity and parental benefits are taxable income — report on your T4E slip. Claim the child care expense deduction in the lower-income parent's name once childcare begins. (3) Ontario provides a Healthy Babies Healthy Children benefit for qualifying new parents. (4) Medical expenses for prenatal care (beyond OHIP coverage), birthing classes, and hospital parking can be claimed on Schedule 1 if total eligible medical expenses exceed the 3% of net income threshold.

First trimester (weeks 1–12): fertilisation and implantation (weeks 1–3), embryo developing major organs (weeks 4–8), heartbeat detectable by ultrasound from week 6, all major organ systems present by week 10, risk of miscarriage highest in this period. Second trimester (weeks 13–27): most parents learn the baby's sex around week 18–20 anatomy scan, fetal movements first felt (quickening) typically weeks 16–22, growth accelerates. Third trimester (weeks 28–40): baby reaches viability (survival outside womb) from about week 24 with medical support, full lung maturity develops, baby repositions head-down in most cases by weeks 32–36. Full term is 39–40 weeks.

Midwifery care is fully funded by OHIP in Ontario and provides continuity of care through a team of 2–3 midwives for low-risk pregnancies, including home or hospital birth options. To find a midwife: search the Association of Ontario Midwives database at ontariomidwives.ca. Demand exceeds supply — connect with a midwife practice as early as possible in pregnancy, ideally before 8 weeks. For obstetric (OB) care: your family doctor provides prenatal care and refers to an OB if risk factors arise. If you have a complex medical history or high-risk pregnancy, ask your family doctor for an OB referral from the start of pregnancy rather than waiting for complications to develop.