Welcome to Verywell’s Pregnancy Week by Week Guide! Your body is designed to do amazing things, but it’s fairly safe to say that all that happens in the 40 weeks of pregnancy are among the most incredible.
While it may sometimes seem like not much is going on (and quite the contrary at other times), each week brings changes big and small that help your baby develop and your body prepare for labor, delivery, and beyond. Pregnancy is marked by three trimesters.
The week by week articles that follow in this guide provide a glimpse into all you can anticipate in these distinct and important phases of your pregnancy, including:
- How your baby is growing and developing
- Your most common pregnancy symptoms
- The best ways to take care of yourself and your baby
- Advice for partners
- What to anticipate at your healthcare practitioner’s office
- Recommended products to consider purchasing
- Special concerns and considerations to be aware of
Whether you’re a first-timer or an experienced mom, you may find pregnancy to be incredible, confusing, overwhelming, and everything in between (sometimes at the same time). With each weekly article, you can trust that you’re learning and focusing on the most important tasks at hand.
We walk you through all you’re about to encounter, step by step, empowering you with what-you-need-to-know, when-you-need-to-know-it information that can help you make sense of it all—and make the decisions that are best for you and your baby.
Start by reading on to get a sense of what each trimester entails, then dig into the individual week by week articles for a closer look at what a difference seven days can make. May your nine months of pregnancy be the healthiest and happiest they can be. We’re honored to be along for the ride.
First Trimester (Weeks 1 to 13)
While this portion of your pregnancy spans three months, it’s considered the shortest trimester. The reason? Many women don’t realize they’re pregnant for the first month. (Home pregnancy tests generally will not register a positive result until about week 4.)
Moreover, week 1 and week 2 are actually the weeks you ovulate and have your menstrual period. So, while the duration of pregnancy consists of 40 weeks, the countdown starts roughly two weeks before you officially become pregnant. (Confusing, we know.)
While you may experience some belly changes, this is usually due to pregnancy-related bloating and gas, not baby growth. Still, by the end of your first trimester, you may gain between 1 and 4½ pounds.
What to Expect
- Early symptoms. The pregnancy hormone human chorionic gonadotropin (hCG) is coursing through your body, doubling every two to three days and peaking at week 10. It’s produced by cells in your growing placenta and spurs the release of the hormones estrogen and progesterone. All of this contributes to a myriad of possible (but not guaranteed) early pregnancy symptoms such as nausea, fatigue, and heartburn. These symptoms tend to wane come your second trimester when hCG levels off.2
- Prenatal appointments. You’ll begin your prenatal appointments this trimester, of course, so it’s important that you have a practitioner you are confident in and comfortable with. There’s no rule that states that the provider who has been giving you your annual check-ups and Pap smears needs to be the one you see throughout pregnancy.
Your Baby’s Development
While your first trimester doesn’t yield much in the way of outward physical changes, a lot is happening that cannot be seen.
Day one of your pregnancy, the sperm and egg have yet to meet. By week 6—halfway through your first trimester—your baby’s tiny face, skull, and brain start to form. His or her hands and feet make their bud-like debut on baby’s tadpole-esque body.
By the close of the first trimester, your baby is more than 3 inches long and sports arms, legs, eyes, a beating heart, and more. In fact, all of the baby’s organs, muscles, limbs, and even genitals are represented. (You won’t learn what your baby’s sex is, however, until week 20.)
Your baby’s circulatory and urinary systems are functioning; the baby’s skeleton begins the slow process of calcifying; their bone marrow is producing white blood cells, and your baby’s vocal cords are progressing toward maturity.
- Start looking for a doctor. If you haven’t already, take this time to start looking into the difference between OB/GYNs and midwives and ask friends and family for recommendations. Once you settle on a practitioner, you can expect to see them every four weeks until the conclusion of your second trimester. (At that point, your visits increase in frequency.)
- Don’t schedule an ultrasound just yet. While you may be looking forward to seeing a sonogram image of your growing baby during your first trimester, you might not be able to. For a majority of pregnant women, a first-trimester ultrasound is not considered a must-do, so you may not see your baby-to-be’s picture until your second trimester. Rest assured, if everything is on track, your baby is developing at a rapid speed right now.
Second Trimester (Weeks 14 to 27)
For most moms-to-be, the middle trimester is considered the easiest. The reason: Your newly-formed placenta is generating more progesterone, a hormone needed to keep your uterine lining baby-friendly.
Labor and Delivery
If everything goes according to plan, you will deliver at around 40 weeks, though many women do so before or after. Your delivery may follow your birth plan to the letter or look entirely different than you have imagined it, perhaps, ending in a C-section when you intended to have a vaginal birth.
Regardless, your body (if not your mind) has been preparing for this moment throughout the course of your pregnancy. Take comfort that you have selected a healthcare practitioner that you can count on, lean on your support team, and communicate your wishes for pain management and more.
Reading more about the final weeks of pregnancy in this guide can help you better understand different labor and delivery scenarios and what you can expect, both during and after.
This day may seem forever away, but it will be here before you know it. And what may have sometimes seemed like the long road you took to get there will be all worth it.