Converting pregnancy from weeks to months gets tricky, because most months aren’t a clean-cut four weeks. It depends on the year, but in general they last about 4.3 weeks, or 30.4 days.
Because the number of days in most months isn’t divisible by 7, it can be tricky to cleanly place a range of weeks into any given month. By these calculations, some months have four weeks, while others have five, which doesn’t make a ton of sense. However, this chart can give you a reasonably close idea of what your weeks pregnant translates to in months. After all, most people will understand you more clearly when you say “four months pregnant” than they will “16 weeks 4 days,” or “116 days past LMP.”
| Trimester | Month | Week |
| First trimester | One | 0-4 |
| Two | 5-8 | |
| Three | 9-13 | |
| Second trimester | Four | 14-17 |
| Five | 18-21 | |
| Six | 22-26 | |
| Third trimester | Seven | 27-30 |
| Eight | 31-35 | |
| Nine | 36-40 (or birth) |
It might be tricky at first to figure out where you are in your pregnancy, but you’ll get the hang of it in no time!
Sources
- “When Your Pregnancy Goes Past Your Due Date.” ACOG. FAQ069 from the American College of Obstetricians and Gynecologists, Jun 2017. Web. Accessed 7/13/17. Available at https://www.acog.org/Patients/FAQs/When-Pregnancy-Goes-Past-Your-Due-Date.
- “Prenatal Development: How Your Baby Grows During Pregnancy.” ACOG. American College of Obstetricians and Gynecologists, Jun 2015. Web. Accessed 7/13/17. Available at https://www.acog.org/Patients/FAQs/Prenatal-Development-How-Your-Baby-Grows-During-Pregnancy#measured.
- A.M. Jukic, et al. “Length of human pregnancy and contributors to its natural variation.” Hum Reprod. 28 (10): 2848-2855. Web. Aug 2013.
