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Home > Learn > Pregnancy > >Do You Need Prenatal Vitamins in the Third Trimester?

Do You Need Prenatal Vitamins in the Third Trimester?

Feb 21, 23 8 min

Prenatal vitamins are essential during your pregnancy, but do you need prenatal vitamins in the third trimester? Read on to understand the benefits.

By Dr. Kenosha Gleaton, OBGYN and fertility expert

Every trimester of pregnancy brings new symptoms, new milestones, and new questions. If you’re curious about how much it really matters for you to continue taking your prenatals in the third trimester, you’ve come to the right place. Let’s dive in. 

An overview of the third trimester

During pregnancy, there are three trimesters or nine months to grow a baby. That might not seem like nearly enough time, and the truth is a lot of development is still incomplete until the last few weeks of pregnancy. The third trimester is the home stretch and includes the period between 28 weeks through 40 weeks. While it can be exciting to count down the days until your due date and finish some last minute shopping, the third trimester can come with some uncomfortable side effects as well. It’s common for moms to experience aches, swollen ankles, pressure on the bladder, and more. Some other common changes you may notice include:

  • An increase in body temperature

  • Increased hair growth and thickness

  • False labor contractions

  • Stretch marks on the stomach, breasts, butt, and legs

  • Leaking nipples (likely colostrum)

  • Decreased sex drive

  • and more!

Aside from the physical changes and sensations you may notice, the third trimester is also a time for your baby to finish growing and developing before childbirth.

Fetal development during the third trimester

Fetal growth begins very early on in your pregnancy and continues until the last few weeks of the third trimester. The baby is growing in size and weight, and by the end of the 40 weeks is likely to be six to nine pounds and 19 to 21 inches long. There are a lot of important milestones in the third trimester, including:

  • Continued development and maturation of the brain, kidneys, and lungs

  • Baby starts to practice breathing

  • Pupils begin to respond to light

  • Fingernails and toenails are visible

  • Coordinated reflexes are possible, including kicking, stretching, and grasping

  • Hair may begin to grow

  • Rapid weight gain begins

  • The head turns downward to prepare for childbirth

By the time you’ve reached your due date, the baby can see, hear, and cry. The lungs finish developing around week 38, and fat is being deposited all over the baby’s body to help keep them warm. 

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Nutrient needs during the third trimester

The American College of Obstetrics and Gynecology (ACOG) recommends eating additional calories during the second and third trimester. Of course caloric needs also increase if pregnant with multiples, but for one fetus, ACOG recommends an extra 340 calories a day starting in the second trimester and increasing a bit more in the third trimester. Calories aren’t all that count though, it’s also vital that you’re eating nutrient dense foods that will continue to support a healthy pregnancy. Read the Natalist blog for more information on nutrition, and articles such as The Importance of Hydration During Pregnancy and What Causes Low Folic Acid

Benefits of prenatal vitamins

Prenatal vitamins should be specifically formulated with the vitamins and minerals necessary for healthy fetal development, including:

  • Calcium for building strong bones and teeth

  • Iron for oxygen and nutrient delivery

  • Iodine, choline, and folic acid for central nervous system development

  • Vitamin D and A for healthy skin and eyesight

  • and more. Read the full prenatal vitamin checklist

While some nutrient needs are more time sensitive during early pregnancy, such as taking folic acid before and during the first trimester, others are vital throughout your entire pregnancy and even into the postpartum period, which is why it's important to find high-quality prenatal gummies or capsules that contain the following ingredients


Iron’s role in the body is to carry oxygen to the tissues. Blood volume increases significantly during pregnancy, which increases the amount of iron you need as well. Without the proper iron supply, it can be difficult to supply your baby with the oxygen they need. Low iron levels can also lead to iron-deficiency anemia, a condition often seen in the third trimester of pregnancy. Anemia can be dangerous for yourself and your pregnancy and may lead to low birth weight, postpartum depression, increased fatigue, and more. 


Calcium is an important mineral known for its role in supporting strong teeth and bones. The body absorbs double the amount of calcium during pregnancy in order to support maternal and fetal needs. Research suggests that close to 80% of fetal calcium stores are absorbed during the final trimester of pregnancy, when the baby’s bones are growing and becoming stronger. Some data also suggests that calcium supplements may improve blood pressure and reduce the risk of preeclampsia, a dangerous condition often seen in the later half of pregnancy. 

Vitamin D

A fat soluble vitamin commonly referred to as the “sunshine vitamin,” vitamin D is vital for calcium absorption in the body as well as other benefits. A study found that taking a supplement with vitamin D during the second and third trimesters of pregnancy was associated with a decreased risk of vitamin D deficiency in newborns. Severe vitamin D deficiency may lead to skeletal deformities such as rickets. 


Docosahexaenoic acid (DHA) is an omega-3 fatty acid that’s known as a critical building block of your baby’s brain and retina. This is especially important to note during the third trimester, a period characterized as critical for optimal brain growth. One study found that women who took omega-3 supplements throughout their pregnancy and up to three months postpartum had children with improved mental development

When can you stop taking prenatal vitamins?

So when is the right time to stop taking a prenatal vitamin, or should you continue taking a prenatal supplement postpartum? Even after you’ve given birth, there are a lot of nutritional needs associated with healing from childbirth, especially if you’re breastfeeding. There are postnatal vitamins that may cater more to your needs as a new mom, especially if you opt to breastfeed, and include similar ingredients to prenatal vitamins, such as DHA, B vitamins, vitamin D, iodine, and choline. 

Research is limited on whether or not a postnatal vitamin can improve milk supply, but there is data to suggest that the quality of breastmilk is improved with a comprehensive multivitamin. Research also suggests that supplementation of certain vitamins and minerals may be associated with decreased postpartum depression, improved cognition, improved immune system, and more. Aside from these health benefits, some data suggests that certain vitamins found in prenatal and postnatal vitamins may be beneficial for the growth and maintenance of hair, skin, and nails following childbirth. 

So, when can you stop taking prenatal vitamins? It’s likely beneficial for you to continue taking some sort of postnatal or multivitamin while you’re breastfeeding, but if you choose not to breastfeed or have stopped breastfeeding, you can switch back to whatever your vitamin regimen was pre-pregnancy. Keep in mind these are just general recommendations, and you should always speak to your healthcare provider for their recommendations specific to you and your body. 

The short answer

The short and sweet answer is yes, you need to take a prenatal vitamin throughout your entire pregnancy. There is still a lot of vital development happening in the third trimester, and it’s important that you’re taking in all the nutrients you and your baby need. The lungs, eyes, brain, and kidneys are still maturing in the final trimester, and you’re at a higher risk for some vitamin deficiencies in the final weeks of pregnancy. It’s recommended that you continue with your vitamin regime for at least a few weeks postpartum, or longer if you’ve decided to breastfeed. Always follow your healthcare provider’s advice for specific recommendations on any medications or supplements, especially while pregnant and breastfeeding. 


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