From the moment a pregnancy is confirmed, what you eat stays on your mind. Taking a multivitamin can feel reassuring, but the parts of the baby that are growing most actively change from stage to stage, and the nutrients needed change with them.
In short, the core of taking supplements through pregnancy is to focus on folic acid early on, iron in the middle stage, and calcium with vitamin D later. It also helps to know which combinations absorb less well when taken at the same time.
01
Why do the supplements I need change as pregnancy progresses?
Key point
The parts of the baby that grow fastest change from one stage of pregnancy to the next, so the nutrients needed change as well. Early on the focus is the neural tube, in the middle stage blood and body weight, and later bones and nerves, so supplements should shift along with them.
It is easy to assume that a single multivitamin will carry you through the whole pregnancy, but in practice the parts of the baby being formed most actively differ at each stage. Covering the nutrients needed at that particular time is far more helpful, which is why it makes sense to divide pregnancy into stages.
Having a clear plan by stage gives you a standard for judging whether the product you are taking is right, without searching every time. Even if there was a period when you could not keep up with everything, adjusting to your current stage of pregnancy is enough, and there is no need to blame yourself.
- Early stage (up to 12 weeks) — the neural tube is forming, so folic acid matters
- Middle stage (13 to 24 weeks) — blood volume and body weight increase, so iron matters
- Later stage (after 24 weeks) — bones and nerves grow firmer, so calcium and vitamin D matter
02
In early pregnancy, how long and how consistently should folic acid be taken?
Key point
Early pregnancy is the critical period when the neural tube, which will become the baby's brain and spinal cord, takes shape, so folic acid intake matters. It is ideal to start 1 month before pregnancy and to continue without missing doses until 3 months into the pregnancy.
The neural tube is the structure that later develops into the brain and spinal cord, and if folic acid is not supplied in sufficient amounts at this time, its formation can be affected. For this reason it is recommended to start folic acid at the planning stage rather than after learning of the pregnancy, so building the habit early in planning is the sensible approach.
If the pregnancy was confirmed late and part of the early period was missed, there is no need for self-blame; continuing folic acid steadily from the time of confirmation until 3 months into the pregnancy is what matters. There is no need to stop it completely after that either, and once the middle stage begins, the priority simply moves toward iron, so there is no cause for worry.
03
How should iron be taken in the middle stage of pregnancy?
Key point
In the middle stage of pregnancy the baby grows quickly and the mother's blood volume rises, so iron can easily fall short. Taking 30mg of iron a day from 16 weeks until 3 months after giving birth is recommended, but it should be taken at a different time of day from calcium.
As the baby begins to grow in earnest and blood volume increases, a shortage of iron can easily bring dizziness and fatigue, which is why anaemia levels are checked at the mid-pregnancy check-up. Taking 30mg of iron a day steadily from 16 weeks until 3 months after giving birth is recommended, and regular check-ups are just as important.
Iron and calcium use the same absorption pathway in the body, so taking them together can make each less effective. It is better to take them separately, about two hours apart, and for the same reason taking iron with milk or other dairy products can also reduce absorption.
- Iron intake — take 30mg a day from 16 weeks until 3 months after giving birth
- Spacing from calcium — the absorption pathways overlap, so take them about two hours apart
- Care with dairy — taking iron with milk or dairy products lowers absorption
04
How should calcium and vitamin D be covered in late pregnancy?
Key point
From around 20 weeks, pregnancy moves into the later stage, when the baby's bones and nerves grow firmer. About 1000mg of calcium a day should be taken together with vitamin D, and ingredients whose safety has not been confirmed should not be added on one's own.
From around 20 weeks, in the middle-to-late period, the baby's bones and nerves firm up much faster than before, so calcium intake needs to rise. At this stage about 1000mg of calcium a day taken together with vitamin D is recommended; a combined preparation can be used, and the amount should be adjusted to the stage of pregnancy.
As the list of things to take grows, it is easy to overlook that some ingredients should be avoided, high-dose vitamin A being the main example. Rather than deciding alone to add products whose safety has not been confirmed, it is safer to have the combination reviewed during a consultation, which is why speaking with the doctor is recommended.
Doctor's view
How the doctor decides
Seeun Cho, Medical Director · Obstetrics & Gynecology Specialist
I do not assume a single multivitamin is enough
I do not conclude that a patient can simply carry on because they are already taking a multivitamin. Because the nutrients needed change at each stage, my first priority is to check whether the product being taken suits the current stage of pregnancy, and if needed I change it to fit the stage and explain the reasons along with it.
For anaemia or fatigue, I check the levels first
I do not tell patients to increase their iron straight away on the basis of dizziness or fatigue alone. Only by checking anaemia levels at the mid-pregnancy check-up first can I tell whether there is a real shortage, so I always look at the test results first and set the dose from them.
If iron and calcium are taken together, I adjust the timing first
For patients who take these two at the same time, I adjust when they are taken before changing the products themselves. Their absorption pathways overlap, so taking them together can make each less effective; I advise leaving about two hours between them and follow up until the habit is settled.
Before adding a new ingredient, I check its safety first
I do not tell patients to add ingredients whose safety has not been confirmed just because there is more to take in late pregnancy. I first recommend reviewing the current supplement combination together during the consultation and keeping only what is needed.
Summary
In summary
In summary, the basics of taking supplements through pregnancy are folic acid early on, iron in the middle stage, and calcium with vitamin D later. Ingredients that share an absorption pathway should be taken at separate times. Even if there was a period when not everything was covered, starting again in line with your current stage is enough, and if you are unsure, it can be checked at your next appointment.
FAQ
Frequently asked questions
I started folic acid late. Does it still help to start now?
The ideal time to start is 1 month before pregnancy, but even if the pregnancy was confirmed late, taking it steadily from now until 3 months into the pregnancy can still help.
Do iron and calcium really need to be taken separately?
The two share an absorption pathway, so taking them together can make each less effective. It is better to take them separately, about two hours apart.
Why is caution needed with vitamin A in late pregnancy?
High-dose vitamin A is regarded as an ingredient whose safety has not been confirmed, so it is safer to have the products you are taking reviewed during a consultation.