Week-by-Week Pregnancy Guide: Trimesters, Due Date and Milestones (2026)
Week-by-Week Pregnancy Guide: Trimesters, Due Date and Milestones A full-term pregnancy runs 40 weeks, split into 3 trimesters — first trimester weeks 1-13, second trimester weeks 14-27, and third trimester weeks 28-40 — and your due date equals the first day of your last menstrual period (LMP) plus 280 days. Weeks pregnant are counted as the number of days since your LMP divided by 7, which is why the count starts about two weeks before conception. Use the Due Date Calculator(/health/due-date-calculator) to turn your LMP into an exact estimated delivery date and trimester timeline. A common arithmetic slip repeats across pregnancy tracking: counting from the day of conception lands two weeks short of what a provider says. Here is the math that clears it up. A person whose LMP was March 1, 2026 is exactly 98 days along on June 7, 2026, and 98 divided by 7 is 14 —...
When Did I Conceive? Understanding Conception Dates and Calculations
When Did I Conceive? Understanding Conception Dates "When exactly did I get pregnant?" Whether you're curious about that romantic getaway, need to know for medical reasons, or are simply piecing together your pregnancy timeline, determining your conception date is a common question. The answer involves a bit of biology and math. Quick answer: Conception typically occurs about 14 days before your next expected period, or roughly 2 weeks after the first day of your last menstrual period (LMP) for those with 28-day cycles. From your due date, you can calculate backwards: conception occurred approximately 266 days (38 weeks) before your due date. A worked example shows how close these calculations can get with good cycle data. Take an LMP of January 3rd with cycles averaging 30 days, tracked with OPKs that showed a positive surge on cycle day 17. Working backwards from an 8-week ultrasound dating, the estimated conception date...
Due Date Calculator: How Accurate Is Your Due Date Really?
Due Date Calculator: How Accurate Is Your Due Date Really? Your due date feels like everything. It's the day you circle on the calendar, count down to, plan around. But here's the reality check most pregnancy books gloss over: Only about 5% of babies are born on their exact due date. Your due date is better understood as a due "window"—most babies arrive sometime between 37 and 42 weeks of pregnancy. The standard 40-week calculation gives you a target, but your baby will arrive when they're ready. This plays out differently for every pregnancy. Consider two examples: a due date set for October 12th based on LMP, then moved to October 8th after an 8-week ultrasound -- with the baby arriving on October 17th, a full 9 days past the adjusted date. In a second pregnancy, the due date was March 22nd, and the baby came at 38 weeks and...
Complete Pregnancy Journey: From Conception to Due Date Calculator Guide
Complete Pregnancy Journey: From Conception to Due Date Two pink lines. A digital "Pregnant." That moment when your whole world shifts. Whether you've been trying for months or this came as a surprise, you probably have one burning question: when is my baby due? The short answer: pregnancy typically lasts 40 weeks (280 days) from the first day of your last menstrual period, or about 38 weeks from conception. For most women, that means a due date roughly 9 months and 1 week from when your last period started. Consider a representative case: 14 months of tracking cycles with OPKs and BBT charts before finally seeing two pink lines on cycle day 29. Cycles ranging from 26 to 33 days make the standard "day 14 ovulation" assumption effectively useless for many women. Across a 39-week pregnancy, cross-referencing every milestone against three different apps and an OB's ultrasound dating -- which...