Pregnancy Week by Week

Pregnancy weeks on a clinic chart start at the first day of the last menstrual period, not at conception. That is why week 1 and week 2 are already on the calendar before an egg is usually released. This page uses that same public convention. It does not listen to a heartbeat, it does not read an ultrasound, and it does not tell you whether a pregnancy is healthy.

Gestational age is the number of full weeks and extra days since that period date. Forty-two days is 6 weeks and 0 days. Forty-four days is 6 weeks and 2 days. The week note matches the completed week: week 6 covers 6 weeks 0 days through 6 weeks 6 days. The first six days, when the completed week is still 0, use the week 1 note so the counter is never blank.

Trimesters on this tool follow a simple cut. The first trimester runs through 13 weeks and 6 days. The second trimester is 14 weeks 0 days through 27 weeks and 6 days. The third trimester starts at 28 weeks 0 days. Hospitals sometimes draw the lines a few days differently. If your chart and this page disagree, keep the chart.

Progress is the share of 280 days that have passed. Two hundred eighty days is 40 weeks, the usual estimated due date from the last period when the cycle is about 28 days. The pregnancy due date calculator on this site can also shift that estimate when the cycle is longer or shorter. This week tool stays on the plain last-period count so the week number is easy to explain.

Only a small share of babies are born on the exact due date. Week 40 is an estimate, not a finish line. Week 37 is often called early term, and week 41 is a week clinicians watch in person. Nothing on this page should be used to decide whether to go to the hospital. Pain, bleeding, a sudden headache, or a baby who is moving much less than usual are reasons to call a local clinician or emergency number, not reasons to refresh a calculator.

The short note under the result is a calendar caption. It mentions what many clinics talk about that week, such as a first visit, a glucose screen, or a birth-place plan. It is not a promise that you will feel a certain symptom. Nausea, kicks, and energy show up on different weeks for different people, and some never follow the textbook list.

If you are still planning a pregnancy, the ovulation calculator estimates a fertile window from cycle length. The guide how to calculate a pregnancy due date walks through the same 280-day idea in sentences. The date difference calculator counts the days between two appointments. All of those pages are educational. A midwife, obstetrician, or family doctor dates a pregnancy with your history and, often, an early ultrasound.