Calculadora de Data Provável do Parto

Estime sua data de parto com base no seu último período menstrual (UPM). Usa a regra de Naegele: UPM + 280 dias.

Overview

An estimated due date is set 280 days — forty weeks — from the first day of the last menstrual period. Naegele's rule reaches the same figure by adding a year, subtracting three months and adding seven days. Dating from a menstrual period rather than from conception means gestational age exceeds embryonic age by about a fortnight throughout the pregnancy.

Data Estimada do Parto

Semana

Semana Atual

w d

Dias Restantes

Trimestre

Concepção Est.

Esta calculadora usa a regra de Naegele (UPM + 280 dias). As datas reais de parto podem variar. Por favor, consulte seu médico para estimativas precisas.

How to Use

  1. 1
    Enter your last period date

    Select the first day of your last menstrual period, or switch to conception or IVF-transfer dating.

  2. 2
    Confirm the cycle length

    Adjust the average cycle length if it differs from the typical 28 days.

  3. 3
    Read your due date

    Your estimated due date, current week, and trimester timeline are shown instantly.

About

The convention uses an imperfect landmark because it is the observable one: the last period is usually recallable, conception is not. The 280-day standard assumes a 28-day cycle with ovulation on day 14, so a materially longer or shorter cycle shifts the true date by the difference. First-trimester ultrasound measurement dates a pregnancy more precisely and supersedes the calculated value where the two disagree beyond a set tolerance.

Trimester boundaries fall at weeks 13 and 27, viability is conventionally placed near week 24, and term spans weeks 37 to 42. Fewer than one birth in twenty occurs on the estimated date itself.

Frequently Asked Questions

How is a pregnancy due date calculated?
The due date is calculated by adding 280 days (40 weeks) to the first day of the last menstrual period (LMP). This is known as Naegele's rule. Only about 5% of babies are born exactly on their due date; most arrive within two weeks before or after.
What are the three trimesters of pregnancy?
The first trimester spans weeks 1–12, the second trimester covers weeks 13–26, and the third trimester is weeks 27–40. Each trimester has distinct developmental milestones and different prenatal care recommendations.
How accurate is a due date calculator?
A due date based on LMP is an estimate. Only 4–5% of babies arrive on the exact due date. An ultrasound in the first trimester can provide a more accurate estimate, typically within 5–7 days. About 80% of babies are born between weeks 38 and 42.

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