Use the MotherToBaby pregnancy calculator and chart below to determine how far along you are and see how your baby develops during pregnancy.
This interactive tool shows when the baby’s body parts could be most sensitive to exposures, and is best displayed on a desktop. Please click on each part of the chart below to learn more about the different terms and colors included. If you need help interpreting this chart or have additional questions about an exposure of concern, please contact a MotherToBaby specialist.
Pregnancy Calculator
Calculate based on:
Enter Last Menstrual Period (LMP) Start
Date:
Exposure Date(s)
(For example, the date(s) you drank alcohol or took a medication)
Click to use last menstrual period (LMP)
Click to use today’s date
Click RESET to erase the dates and start over
Please note days and weeks of pregnancy are an estimate only (timing depends on each pregnant person’s menstrual cycle, ovulation, and implantation; which can vary). Additionally, information on when birth defects can occur is based on sparse data and subject to limitations. The information presented above is an estimate only, and some variation is expected.
Learn More About Critical Periods
Understanding Critical Periods
Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. Pregnancy problems (like miscarriage) can also happen in any pregnancy. Sometimes, exposures like medications, drugs, alcohol, and infections can increase the chance for birth defects or pregnancy complications. However, for an exposure to cause a problem, it generally has to happen during the “critical period” when a body part is forming. The dose, frequency, and the way the exposure enters the body (swallowed, breathed in, put on the skin, etc.) can also play a role. We look at research studies to try to understand if a certain exposure might increase the chance of birth defects or other problems in a pregnancy. Learn more by reading our Critical Periods of Development Fact Sheet.
Using the Calculator and Chart
This chart shows when different parts of a baby’s body form during pregnancy and when birth defects or pregnancy complications might happen. By entering the first day of your last menstrual period (LMP), the calculator can estimate how far along you are today. It can also tell you if an exposure happened during a critical time in your baby’s development.
Various Factors Play a Role
Exposures are not a common cause of birth defects. Genetics, age of the parents, health conditions in the pregnant person, and a combination of these factors can also play a role in fetal development. Additionally, even when an exposure of concern takes place during the critical period, not every baby will be affected by a birth defect. Once a body part has formed, exposures are less likely to cause birth defects. However, as the baby continues to grow and develop in the second and third trimesters, some exposures can cause problems with how the body part works. Problems with the baby’s growth or early (preterm) delivery might also happen as the pregnancy continues.
Limited Data
Research on early development is limited. The chart gives a general idea of when an exposure could cause a birth defect, but individual differences are expected. Our team can help you understand the timing of your pregnancy and review any exposures you have had. For a personalized assessment, contact MotherToBaby by phone, chat, text, or email.
References
- Ackerman S. Discovering the Brain. Washington (DC): National Academies Press (US); 1992. 6. The Development and Shaping of the Brain. Available from: https://www.ncbi.nlm.nih.gov/books/NBK234146/
- American College of Obstetricians and Gynecologists (2024). Facts Are Important: Understanding and Navigating Viability. Retrieved from: https://www.acog.org/advocacy/facts-are-important/understanding-and-navigating-viability
- Centers for Disease Control and Prevention. (2024). Specific Birth Defects and Other Health Conditions. Retrieved from: https://www.cdc.gov/birth-defects/about/types.html
- Hales, B., Scialli, A., & Tassinari, M. (Eds.). (2018). Teratology Primer, 3rd Edition. Society for Birth Defects Research and Prevention. https://www.birthdefectsresearch.org/primer/
- Helwany M, Arbor TC, Tadi P. Embryology, Ear. [Updated 2023 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557588/
- Libretti S, Aeddula NR. Embryology, Genitourinary. [Updated 2023 Feb 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559309/
- Malhotra R, Malhotra B, Ramteke H. Enhancing Omphalocele Care: Navigating Complications and Innovative Treatment Approaches. Cureus. 2023 Oct 25; 15(10):e47638. doi: 10.7759/cureus.47638. PMID: 38021990; PMCID: PMC10667945.
- Moore, KL, Persaud, TVN, Torchia MG. (2013). The Developing Human: Clinically Oriented Embryology (9th Ed.). Saunders.
- Open AI (2024). ChatGPT (June version) [Large Language Model]. https://chat.openai.com/chat
- Rentea RM, Gupta V. Gastroschisis. [Updated 2023 Apr 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557894/
- Sadler, T.W. (2014). Langman’s Medical Embryology (13th Edition), Philadelphia, PA: Wolters Kluwer.
- Singh R, Munakomi S. Embryology, Neural Tube. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK542285/
- Tickle C. How the embryo makes a limb: determination, polarity and identity. J Anat. 2015 Oct; 227(4):418-30. doi: 10.1111/joa.12361. Epub 2015 Aug 7. PMID: 26249743; PMCID: PMC4580101.
- Zaontz, M, Packer M. ABNORMALITIES OF THE EXTERNAL GENITALIA, Volume 44, Issue 5, 1997, Pages 1267-1297, ISSN 0031-3955. DOI: https://doi.org/10.1016/S0031-3955(05)70557-5
Get the Facts
Our MotherToBaby Fact Sheets offer the most current information on exposures in pregnancy and breastfeeding.
Browse Studies
Explore our ongoing pregnancy studies by health condition or medication to find the right one for you.
Ask Our Experts
Call, text, chat, or email for a free personalized risk assessment on exposures in pregnancy and breastfeeding.