When should you start taking prenatals? Before conception? After? What time of day should you take them? Read our detailed guide and find out.


By Dr. Mare Mbaye

When to start taking prenatal vitamins

Most women are aware that prenatal vitamins are an important part of a healthy pregnancy. What a lot of them don’t know is that they should be taking them before conceiving. In fact, according to the Centers for Disease Control & Prevention (CDC), all women between ages 15 and 45 should be taking 400 micrograms (mcg) of folate. That recommendation isn’t just from the CDC either. The American College of Obstetricians and Gynecologists (ACOG) also recommends folate supplementation to any woman who may become pregnant. Here's more on the best time to take prenatal vitamins.

The ideal time to start a prenatal is one to three months before trying to conceive.

The main reason for this is due to the large number of unintended pregnancies. A study published in 2016 revealed that a staggering 45% of pregnancies in the US are unplanned. The window during which folate supplementation is most important is in the first 21 to 28 days after conception, which is way before many of these pregnancies are unrecognized. It’s no wonder this recommendation was made as a precaution of sorts. Since a prenatal supplement contains key nutrients for both the pregnant person and the growing baby, taking it one to three months before trying to conceive is ideal.

I will pause a moment here to say that if you are a reproductive age woman who is not trying to get pregnant and is on reliable birth control (sorry, condoms don’t count), then this recommendation isn’t necessarily applicable.

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The first 3 to 4 weeks of pregnancy

Essential prenatal vitamins are also crucial during the first three to four weeks of pregnancy. Why are those first three to four weeks of pregnancy so important? The neural tube is the precursor structure that will eventually become the brain, spine, and spinal cord in the fetus later on in the pregnancy. Neural tube defects like spina bifida (a birth defect at the base of the spine) and anencephaly (a birth defect the brain) occur when the neural tube doesn't close when it is supposed to. Neural tube closure is usually complete by the 28th day after conception—which, if the pregnancy wasn’t planned, is likely well before a woman knows that she’s pregnant. As the most common major malformation of the central nervous system, this is an important risk to consider and try to prevent.

Like most things in life, taking folate isn’t a guarantee. However, several clinical trials (you can read more about them here, here, and here) have shown that adequate folic acid consumption by women around the time of conception prevents a substantial proportion of neural tube defects. 

The other nutrients in prenatal vitamins aren’t quite as time-sensitive, so I won’t delve into them here, but you can check out this article to learn more.

Can you still take prenatal vitamins if already pregnant?

So you might be wondering, what happens if I'm already pregnant? Is it too late to start taking a prenatal? The answer is no. The recommendation is to take prenatal vitamins as soon as you know you're pregnant and throughout the remainder of your pregnancy. Pregnancy is not an easy road (despite what TV shows and movies portray), and it takes a toll on the body of a pregnant woman.

A pregnant woman simply requires higher amounts of certain key nutrients while supporting the fetal development. This makes a lot of sense when you think about the fact that the body is suddenly tasked with not only providing for itself but also for a whole new life that it literally started from scratch. It’s pretty amazing, right? The best way we have to help the body out is to provide it with the nutrients it needs, in the right amounts. 

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Prenatals after pregnancy and during breastfeeding

Additionally, many providers recommend that women supplement with postnatal vitamins during the postpartum period. Surprisingly, there is no universal recommendation for exactly when to stop taking a prenatal vitamin. While all agree that vitamin D and iron supplementation postnatally is very important, there is no agreement on folate supplementation. The World Health Organization (WHO) does suggest continuing prenatal vitamins for as long as you breastfeed, and ACOG notes that this is a common recommendation by OBGYNs.

Taking prenatal vitamins while breastfeeding is thought to be helpful because it ensures you're getting the essential vitamins and minerals you need. All the necessary nutrients can be obtained from food if you're eating a well-balanced diet—but let’s be real, that can be tough when you're not only taking care of a newborn, but also a home and a career. A daily prenatal vitamin bridges any nutritional gaps that may exist in your diet while allowing you to worry about one less thing in your busy day.

Benefits of continued prenatal supplement

According to a study published in 2012, there are significant benefits to continuing to take a prenatal through breastfeeding—specifically due to DHA, folate, vitamin D, and iodine. In the study, continued supplementation through the breastfeeding period led to better visual, cognitive, and motor development in the infant. The simple theory here is that a breastfed baby is getting all its nutrients from breastmilk during this time, which means the nutrient intake in mom translates to the nutrient intake in the baby. 

What if you’re not breastfeeding? In that case, a prenatal vitamin isn’t necessary. A regular adult multivitamin is still a good idea, but it’s for your nutrition and not the baby’s in this case. Your baby should receive all the nutrients they need from fortified infant formula. 

The best time of day to take your prenatal

Now that we’ve established why prenatals are so important to take—before, during and sometimes after pregnancy—let’s talk about when to take it on a daily basis.

So when is the best time to take prenatal vitamins during the day? The short answer is: whenever you’re the most likely to remember to take it! There’s no best “time” to take a prenatal vitamin in general, but that doesn’t mean there may not be a specific time that’s best for each woman. For some, it may be in the mornings with breakfast, while for others it may be with dinner or at bedtime. Certainly, don’t worry about whether a particular time of day is best for absorption; your body absorbs nutrients from what you take all day, everyday. 

If you have any questions or concerns about starting a prenatal vitamin, running it by your provider is always a good idea. And especially if you have no idea where to begin the search for the right prenatal vitamin for you, a trusted provider can be a great resource to rely on.