Understanding the Different Stages of Pregnancy: First, Second, and Third Trimester

One of the first things newly expectant women do is calculate their due date. Not only is learning your due date exciting, but it also provides practical information, such as what stage of pregnancy you’re in. The stages of pregnancy are often called trimesters since there are three of them, broken down by week.

Because many developmental milestones and prenatal tests are referenced in terms of trimester, our team here at OBGYN Westside, PLLC, on the Upper West Side of New York City wants to make sure you have a good understanding of what the different stages of pregnancy mean. 

First trimester

The first trimester is your first 13 weeks of pregnancy. Your due date is calculated according to the first day of your last menstrual period; dating is verified by ultrasound during your first visit at 7-8 weeks from your last period. Pregnancy lasts about 40 weeks.

Although you won’t look pregnant yet, the first trimester is the most crucial to your baby's development. During your first trimester, your baby's body structure, skeletal system, and organ systems develop. 

Your baby’s neural tube (the foundations of your baby’s brain and nervous system) may have even formed before you realized you’re pregnant. This is why it’s important to take prenatal vitamins if you’re trying to conceive 一 to supply your body with plenty of folate to help reduce neural tube defects.

Your baby is going through tremendous growth during this phase, and your body is changing to prepare for your baby’s continued growth. 

These changes, especially the shifting hormones, cause symptoms such as morning sickness, fatigue, sore breasts, and frequent urination. Keep in mind that you may not experience all of these symptoms. Each woman is different and each pregnancy is different. 

Second trimester 

Your second trimester lasts from weeks 14-26, and this trimester is often dubbed the “golden trimester.” Your pesky first-trimester symptoms have started to fade, your energy levels have come back up, and it’s still relatively easy to move around. 

Even though morning sickness and fatigue dissipate, you may experience other symptoms such as round ligament pain, heartburn, constipation, and back pain. 

Your baby continues to grow and develop reflexes, like sucking. Babies are about three pounds (on average) at the end of the second trimester, that’s 7 times more than the start of this trimester!

Many moms look forward to the second trimester because you can schedule your anatomy ultrasound and find out if you’re having a boy or girl. You can also usually start to feel your baby’s movements after 20-22 weeks.

Third trimester

The third trimester is the home stretch! Your third trimester lasts from week 28 up until your baby is born. Your baby is considered full term at 37 weeks, and most women give birth anywhere from 37-42 weeks. 

During your third trimester, your baby continues to grow and prepare their lungs for breathing after birth. 

You may experience physical symptoms such as hemorrhoids (from the pressure of your growing uterus), urinary incontinence, varicose veins, sleeping problems, more heartburn, and shortness of breath. 

Prenatal care through each trimester

Because your needs change with each trimester, so does your prenatal schedule. During your first trimester, our team establishes your pregnancy with a dating ultrasound, checks your hormone levels with blood tests, and provides guidance on nutrition and prenatal vitamins.

You’ll have various tests throughout each trimester including ultrasounds, genetic tests, non-stress tests, and glucose testing, but rest assured that our team guides you through all the fine details like when to schedule tests and where to receive them.

As your due date approaches, you’ll have more frequent routine check-ups. Near the end of your pregnancy, you’ll schedule weekly visits with us. 

Questions? Give us a call today or book your appointment online.