Congratulations on your growing bundle! As exciting as pregnancy is, it can also be a little overwhelming...but you don't have to go it alone! We're here for you (and your bump) every step along the way with expert advice and tips from celebrated pediatrician Dr. Harvey Karp.

How can I calculate my pregnancy week?

You start calculating your pregnancy from the first day of your last menstrual period (LMP). So, if your LMP was September 1st, week 2 of pregnancy begins September 8th, week 3 of pregnancy begins September 15th, week 4 of pregnancy begins September 22nd, and so on until you reach your estimated due date (EDD) at the end of 40 weeks. 

You can estimate your due date by looking at the date your last period started. Then, add seven days. Then count back three months. So, if September 1st was the start of your last period, add a week (that brings you to September 8th). Then count back three months, which brings you to roughly June 8th—your estimated due date. Of course, this assumes a typical cycle of 28 days with spontaneous conception at day 14…so there’s lots of factors that could change this. Your doctor will be able to give you a slightly more accurate prediction—and even then, it’s important to know that only 5% of pregnant folks give birth on their exact due date!

How long is a pregnancy weeks-wise?

A typical pregnancy is 40 weeks long and starts with the first date of your last menstrual period. But because we start counting pregnancy weeks from your last period, that means that you aren’t actually pregnant for weeks 1 and 2 of pregnancy. 

Which is week 1 of my pregnancy?

When you were technically “1 week pregnant” you were not pregnant at all! In fact, you were probably still menstruating and wouldn’t conceive your little one until about two weeks later (in a typical 28-day cycle, ovulation begins around day 14—but in real life, this varies from person to person).  Most folks conceive around week 3 and get a positive pregnancy test around week 4 or 5.

First Trimester: Pregnancy Week by Week

Welcome to the first trimester! At the very beginning of your pregnancy journey, your little one is no bigger than a grain of sand…but by the end of the first trimester, they’ll be the size of a lime! While you might not have a full, round belly to show for your pregnancy yet, you probably are sensing your body changing. In addition to feeling excitement and joy, you may be exhausted and even a little nauseous, too (here are some tips for easing morning sickness!). At the end of the first trimester a lot of parents choose to share their pregnancy news with loved ones—if that feels right for your family, here are some fun pregnancy announcement ideas.

Second Trimester: Pregnancy Week by Week

Ah, the second trimester. For many expectant parents, the second trimester is a golden period: The fog of first trimester nausea and fatigue begins to fade, and the discomfort of the third trimester has yet to settle in. If you’re experiencing this burst of energy, now’s a good time to start checking to-dos off your list…like starting your baby registry, thinking about baby names, and dropping hints if you’re hoping for a baby shower. You’ll have some important doctor visits during this time, too, including your anatomy scan (for many families, this is when you find out your baby’s gender) and glucose test, which screens for gestational diabetes

Third Trimester Pregnancy Weeks

Woo-hoo! You’ve entered the third trimester of pregnancy, which means you’re in the homestretch! Some fair warning: These last weeks of pregnancy tend to creep by as your babe-on-the-way can be increasingly demanding on your body. As much as you can, rest and take care of yourself. And if partnered, consider carving out some one-on-one time (perhaps with a babymoon!)…because pretty soon you’ll have a little lovebug vying for your attention. Lots of parents-to-be get the urge to nest during these final weeks, which might give you the final boost you need to get pre-baby projects (like installing the car seat, decorating the nursery, and preparing for labor) across the finish line. Know that even as these days may feel interminable, there’s a very bright light at the end of the tunnel. You’ve got this!

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Disclaimer: The information on our site is NOT medical advice for any specific person or condition. It is only meant as general information. If you have any medical questions and concerns about your child or yourself, please contact your health provider.