The Pregnancy Calculator can estimate a pregnancy schedule based on the provided due date, last period date, ultrasound date, conception date, or IVF transfer date.
Pregnancy Term & Due Date
Pregnancy usually lasts about 40 weeks (280 days) from the first day of your last menstrual period (also called LMP) to your due date. Your due date is the date that your provider thinks you will have your baby.
The American College of Obstetricians and Gynecologists (also called ACOG) and the Society for Maternal-Fetal Medicine (also called SMFM) define a full-term pregnancy as a pregnancy that lasts between 39 weeks, 0 days and 40 weeks, 6 days.
This means your pregnancy lasts between 1 week before your due date and 1 week after your due date. Babies born full term have the best chance of being healthy, compared with babies born earlier or later.
ACOG and SMFM use these definitions to describe term pregnancies:
- Early term: Your baby is born between 37 weeks, 0 days and 38 weeks, 6 days.
- Full term: Your baby is born between 39 weeks, 0 days and 40 weeks, 6 days.
- Late term: Your baby is born between 41 weeks, 0 days and 41 weeks, 6 days.
- Postterm: Your baby is born after 42 weeks, 0 days.
How was the length of pregnancy defined in the past?
In the past, a pregnancy that lasted anywhere between 37 and 42 weeks was called a term pregnancy. Health care providers once thought this 5-week period was a safe time for most babies to be born.
In 2013, ACOG and SMFM updated the definitions for term pregnancies because research shows that every week of pregnancy counts for the health of your baby. Lots of important things happen to your baby in the last few weeks of pregnancy.
For example, your baby’s brain and lungs are still developing. Being pregnant for at least 39 weeks gives your baby’s body the time it needs to grow and develop.
These definitions can help more babies be born healthy by helping to prevent births that are being scheduled a little early for non-medical reasons. If your pregnancy is healthy, wait for labor to begin on its own.
How to do a pregnancy test?
A pregnancy test is a way to determine if you’re pregnant. If your pregnancy test is positive, it means you’re pregnant. If the test is negative, it means you aren’t pregnant. Pregnancy tests work by detecting human chorionic gonadotropin (HCG), a hormone your body makes when you’re pregnant.
From the very beginning of pregnancy, your body starts to go through changes to support the cells that will develop into your baby. One thing that happens very quickly is the production of HCG. If you’re pregnant, your body starts to produce more HCG. Your HCG levels start to build up once the fertilized egg implants in your uterus, about six to 10 days after conception.
There are two main types of pregnancy tests, urine tests and blood tests. Often, you’ll take a urine test at home with a home pregnancy test. This type of test is available over the counter (you don’t need a prescription from your healthcare provider) and in a variety of price ranges.
Blood tests to check for pregnancy happen in your healthcare provider’s office and involve giving a sample of your blood. The other way to confirm a pregnancy is by using an ultrasound. Your provider performs an ultrasound in their office.
There are several reasons why you might take a pregnancy test. You could be trying to get pregnant and hoping for a positive result. You might have experienced an issue with your birth control.
You might even be about to have a medical procedure or start a new medication that could be complicated by pregnancy. No matter what the reason, if you ever have any questions about your test results, the best thing to do is reach out to your healthcare provider.
What hormone levels are checked for a pregnancy test?
Pregnancy tests look for an elevated amount of HCG. Levels of HCG rise quickly – doubling every few days in the first weeks of pregnancy. The placenta produces HCG. Only pregnant women have a placenta, which develops shortly after a fertilized egg attaches to the uterine wall.
When should I take a pregnancy test?
If you think you could be pregnant, it’s a good idea to take a test and make sure. Home pregnancy tests can differ in how early they’ll detect a pregnancy. In many cases, you might get a positive result from an at-home test as early as 10 days after conception.
For a more accurate result, wait until after you’ve missed your period to take a test. Remember, if you take a test too soon, it could be negative even if you’re pregnant. If you get a negative test and then miss your period, take another test.
What time should I take a pregnancy test?
In general, the best time is when you have your first morning pee. However, some pregnancy tests are sensitive enough to detect HCG no matter what time of day you take the test.
When possible, try to wait until it’s been three hours since your last pee before you take the test. You could also take two pregnancy tests to confirm you get the same result.
Pregnancy Management
Managing pregnancy involves balancing multiple personalized factors like medications, weight changes, physical activity, and diet, all tailored to an individual’s health profile.
Medication:
Medications during pregnancy require careful evaluation due to potential impacts on fetal development. The FDA’s traditional A, B, C, D, and X pregnancy categories were phased out in 2015 in favor of more descriptive labeling, which details risks, benefits, and available data from human and animal studies.
Category A drugs (safest, proven safe in humans) are rare, while category X (high fetal risk outweighing benefits) demands avoidance. Always discuss all prescriptions, over-the-counter drugs, and supplements with your healthcare provider, who can reference resources like the Drugs in Pregnancy and Lactation database for evidence-based advice.
Weight Gain:
Appropriate weight gain supports healthy fetal growth, including baby size, amniotic fluid volume, and maternal stores of fat and protein.
Too little gain risks low birth weight and preterm birth; excess can lead to gestational diabetes, preeclampsia, or C-section. The Institute of Medicine (IOM) guidelines, reaffirmed in recent studies, recommend:
| Pre-Pregnancy BMI | Total Weight Gain Range |
|---|---|
| Underweight (<18.5) | 28–40 lbs (12.7–18.1 kg) |
| Normal (18.5–24.9) | 25–35 lbs (11.3–15.9 kg) |
| Overweight (25–29.9) | 15–25 lbs (6.8–11.3 kg) |
| Obese (≥30) | 11–20 lbs (5–9 kg) |
Track progress with tools like pregnancy apps, aiming for steady weekly gains (e.g., 0.5–1 lb in the second/third trimesters for normal BMI).
Exercise:
Regular exercise during pregnancy boosts cardiovascular health, reduces gestational diabetes risk by up to 30%, and may shorten labor while lowering C-section odds.
The American College of Obstetricians and Gynecologists (ACOG) recommends 150 minutes weekly of moderate aerobic activity (like brisk walking or swimming) plus strength training for uncomplicated pregnancies.
Pre-pregnancy athletes can often maintain intense routines, such as running or cycling. Stop and call your doctor for warning signs: dizziness, blurred vision, persistent shortness of breath, abdominal pain, sudden swelling, or contractions.
Nutrition:
Pregnancy heightens needs for calories (extra 340–450 daily in later trimesters) and key nutrients to fuel placental growth and fetal organ formation.
Folic acid (600 mcg/day) slashes neural tube defect risks by 70%; iron (27 mg/day) prevents maternal anemia; calcium (1,000 mg/day) builds baby bones; and DHA (200–300 mg/day from fatty fish or algae supplements) supports cognitive development.
Prioritize whole foods: leafy greens, lean proteins, dairy or fortified alternatives, nuts, and berries. Avoid raw sushi, unpasteurized dairy, and high-mercury fish. Work with a registered dietitian for a customized plan, especially if managing conditions like nausea or food aversions.
Pregnant individuals should partner with their obstetrician for holistic guidance suited to their unique circumstances.