Pregnancy Calculator
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 describes the roughly nine‑month period during which a fetus—or multiple fetuses—develops inside a woman's uterus. Birth typically happens about 38 weeks after conception, which corresponds to around 40 weeks from the first day of the last menstrual period. The WHO considers a full‑term pregnancy to be between 37 and 42 weeks. At the initial OB‑GYN appointment, the physician usually gives an estimated delivery date, often based on an ultrasound, though it can also be calculated from the woman's last menstrual period.
Although clinicians can project a due date, the actual duration of a pregnancy is influenced by many factors such as the mother's age, her previous pregnancy lengths, and her weight at delivery.1 Additional variables that cause natural variation are still not fully understood. Research shows that less than 4 % of births happen on the exact predicted day, about 60 % occur within a week of that date, and nearly 90 % fall within two weeks.2 Consequently, while we can be reasonably sure a baby will arrive within a fortnight of the estimated date, pinpointing the precise day remains impossible.
Pregnancy Detection
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 testing relies on detecting hormones—mainly hCG—that appear only after fertilisation. Both blood and urine specimens can reveal a pregnancy as early as six to eight days post‑conception. Blood tests performed in a clinic are more sensitive; they can quantify the exact hCG level and detect it in smaller amounts, but they take longer and cost more than over‑the‑counter urine kits. Clinical urine tests are also available, though they are not necessarily more accurate than home kits and may be pricier.
Pregnancy Management
There are a number of factors that need to be considered during pregnancy, many of which are highly dependent on the individual's situation, such as medication, weight gain, exercise, and nutrition.
Medication:
Using certain drugs while pregnant can have lasting consequences for the developing fetus. In the United States, the FDA sorts medications into categories A, B, C, D, and X according to the balance of maternal benefit versus fetal risk. Category A drugs offer clear benefits to the mother with minimal fetal danger, whereas Category X drugs pose proven, serious risks to the fetus that outweigh any maternal advantage. Pregnant individuals should always discuss any planned medication with their healthcare provider.
Weight gain:
Exercise:
Research shows that staying active with aerobic exercise during pregnancy can help maintain fitness and may lower the chance of a cesarean section. While recommendations differ among women, regular cardio and strength training are generally advised for expectant mothers, especially those who exercised before conceiving and have uncomplicated pregnancies—they can usually continue moderate‑to‑high‑intensity workouts.4 The American College of Obstetricians and Gynecologists notes that, in an uncomplicated pregnancy, exercise is unlikely to cause fetal injury. Nonetheless, women should stop and seek medical advice if they experience any of the following: vaginal bleeding, breathlessness, dizziness, headache, calf pain or swelling, leaking amniotic fluid, reduced fetal movement, signs of pre‑term labor, muscle weakness, or chest pain.5
Nutrition:
What a pregnant person eats plays a crucial role in the wellbeing of both mother and baby. Pregnancy raises overall energy needs and creates specific requirements for certain micronutrients.6
Key nutrients such as folic acid (vitamin B9) lower the risk of neural‑tube defects, while DHA, an omega‑3 fatty acid essential for brain and retinal development, must be supplied through the placenta during pregnancy or via breast‑milk after birth. Numerous other vitamins and minerals support proper fetal growth, and information on safe foods and habits can be overwhelming and vary individually. Expectant mothers are encouraged to consult a physician or a registered dietitian to tailor nutrition plans to their personal circumstances.
- Jukic, AM, Baird, DD, Weinberg, CR, et al. 2013. "Length of human pregnancy and contributors to its natural variation. Human Reproduction 28(10): 2848-55. PMC3777570.
- Moore, Keith. 2015. "How accurate are 'due dates'?" BBC, February 3, 2015. bbc.com/news/magazine-31046144.
- Institute of Medicine (2009). “Weight Gain During Pregnancy: Reexamining the Guidelines.” National Academies Press.
- Davies, GA, Wolfe, LA, Mottola, MF, et al. 2003. "Exercise in pregnancy and the postpartum period." Journal of Obstetrics and Gynaecology Canada 25(6): 516-29.
- Artal, R., O'Toole, M. 2003. "Guidelines of the American College of Obstetricians and Gynecologists for exercise during pregnancy and the postpartum period." British Journal of Sports Medicine 37: 6-12. doi:10.1136/bjsm.37.1.6
- Lammi-Keefe, CJ, Couch, SC, Philipson, E. 2008. "Handbook of Nutrition and Pregnancy." Humana Press.