Calculate your due date, current week of pregnancy, trimester, milestones and complete 40-week timeline.
Pregnancy is a term used to describe a woman's state over a time period (~9 months) during which one or more offspring develops inside of a woman. Childbirth usually occurs approximately 38 weeks after conception, or about 40 weeks after the last menstrual period. The World Health Organization defines a normal pregnancy term to last between 37 and 42 weeks.
During a person's first OB-GYN visit, the doctor will usually provide an estimated date (based on a sonogram) at which the child will be born, or due date. Alternatively, the due date can also be estimated based on a person's last menstrual period, IVF transfer date, or ultrasound dating.
This calculator supports five common methods for estimating pregnancy timeline:
If you already know your estimated due date (from an ultrasound or doctor visit), enter it directly. The calculator will reverse-engineer all other dates including last menstrual period, conception date and the complete week-by-week timeline.
This is the most common dating method. Pregnancy is conventionally counted from the first day of the last menstrual period, even though conception occurs approximately two weeks later. A standard pregnancy is 280 days (40 weeks) from LMP.
If you know the exact date of conception (for example from fertility tracking), you can calculate the full pregnancy timeline. Pregnancy from conception is approximately 266 days (38 weeks).
For pregnancies conceived via in vitro fertilization (IVF), the most accurate dating uses the embryo transfer date combined with the embryo age at transfer. Day 3 and day 5 embryos are the most common.
If you have had an ultrasound scan where the fetus was measured and a gestational age was assigned, you can use that measurement to calculate your estimated due date. First-trimester ultrasounds are generally considered the most accurate for dating.
| Trimester | Week Range | Key Developments |
|---|---|---|
| First Trimester | Week 1 – Week 12 | Conception, implantation, heartbeat develops, all major organs begin forming, highest miscarriage risk |
| Second Trimester | Week 13 – Week 27 | Movement felt, gender detectable, hearing develops, viability increases significantly |
| Third Trimester | Week 28 – Week 40+ | Lung maturation, rapid weight gain, brain development, position for birth |
Pregnancy can be detected either by using pregnancy tests or by the woman herself noticing a number of symptoms, including a missed menstrual period, increased basal body temperature, fatigue, nausea, and increased frequency of urination.
Pregnancy tests involve the detection of hormones that serve as biomarkers for pregnancy and include clinical blood or urine tests that can detect pregnancy from six to eight days after fertilization.
Taking certain medications during pregnancy can have lasting effects on the fetus. In the U.S., drugs are classified into categories A, B, C, D, and X by the FDA based on potential benefits vs. fetal risks. A person that is pregnant should consult their doctor regarding any medications they plan to use during their pregnancy.
The Institute of Medicine recommends: 25-35 lbs for normal BMI, 28-40 lbs for underweight, 15-25 lbs for overweight, and 11-20 lbs for obese women.
Studies indicate that aerobic exercise during pregnancy helps to improve or maintain physical fitness as well as possibly decreasing the risk of C-sections. Consult a doctor if you experience vaginal bleeding, shortness of breath, dizziness, calf pain, decreased fetal movement or preterm labor symptoms.
Folic acid (Vitamin B9) helps decrease the risk of neural tube defects. DHA omega-3 is necessary for proper brain and retinal development. Pregnant women should consult their doctors and/or dietitian for personalized nutrition advice.
All dates and milestones are estimates based on average 28-day cycles and standard 40-week pregnancy term. Actual pregnancy length varies naturally between 37 and 42 weeks. Ultrasound dating in the first trimester is generally more accurate than LMP dating. This calculator is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider for personalized prenatal care and due date confirmation. Results for multiple pregnancies differ significantly from single pregnancy estimates.