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When to Start Prenatal Vitamins & What to Look for: Women Over 35


Doctors recommend starting on prenatal vitamins 3 months before you plan to get pregnant, as a part of your preconception preparation. Building a solid foundation for pregnancy during the preconception period is even more important for women over 35 – as our nutritional needs, as well as our ability to absorb and utilize the nutrients from food change with age. Here are the 4 preconception priorities for women over 35 who are getting started on prenatal vitamins.


1. Maintain strong bone and teeth

Throughout our adolescence and 20s, we build our bones and teeth. Bone density typically peaks at around age 25 for women, and stays relatively stable until age 50 or so. However, formation of new bones starts slowing down in our 30s. So, once you hit 35, it’s important to sustain the bone mass you’ve built up in your 20s.

Maintaining strong bones (and teeth) becomes even more important when preparing for a pregnancy. Once you get pregnant, the developing baby will depend entirely on the calcium in your system to build bones and teeth. When there isn’t enough calcium in your diet (and in your prenatal vitamins), you can start losing your bone mass to support the growth of the baby. 

Make sure your prenatal vitamins contain Calcium, Vitamin D and Vitamin K in impactful doses and in forms that are easier for the body to absorb and utilize.



  • Our ability to absorb calcium slows as we age. One study that aggregated nutritional surveys conducted in wealthy countries found that about 44% of women between 31 and 50 have inadequate intake of calcium. Other studies found lower but still not-negligible prevalence in the 10-15% range.
  • The recommended daily amount of calcium is 1,000 mg/day. It’s a relatively easy mineral to get from food sources like dairy and fortified foods (orange juice, fortified plant milk, etc.), but it’s a good idea to select prenatal vitamins with a little bit of calcium to ensure you get enough each day.
  • Calcium, like many minerals, can be difficult to absorb. Some high-quality prenatal vitamins use chelated forms of calcium (calcium molecules bound to organic compounds or amino acids) to help with absorption.


Vitamin D


2. Get ready for blood volume increase

Already in the first few weeks of a pregnancy, the volume of blood increases significantly to supply vital oxygen to the growing baby. By the end of the pregnancy, your blood volume will increase by 45% on average, with some women seeing a doubling of their blood volume.  So it’s important to prepare your body during the preconception period for this increased demand. For women over 35, three prenatal vitamin ingredients are key: Iron, Vitamin C and Vitamin B12.




  • Iron is the building block of hemoglobin, the oxygen carrier within the red blood cells. Of all age groups, women over 35 are the most likely to be low in iron: Studies estimate about 15% of women 35+ to have inadequate amount of iron in their diet. A whopping 96% of women don’t get enough iron during pregnancy.
  • The recommended daily amount of iron is 27 mg for pregnant women. Because too much iron can make morning sickness worse and lead to gastrointestinal problems, more is not better. Follow your doctor’s recommendation.
  • Like calcium and other minerals, iron is difficult for the body to absorb. (This is one reason prenatal vitamins can trigger nausea.) Look for prenatal vitamins with chelated iron to mitigate these side effects.


Vitamin C


Vitamin B12

  • Low levels of vitamin B12 can – indirectly, through enzymatic pathways involved in how your body uses folate – lead to low production of red blood cells in the bone marrow.
  • Inadequate Vitamin B12 levels are less common than the other nutrients in this list, but deficiency risks increase with age. If you’ve been taking birth control pills, that’s an additional risk factor for low B vitamins, including folate (B9) and B12.
  • The daily recommended amount of Vitamin B12 is 2.6 mcg.


3. Support egg health & ovarian health

Women over 35 are less likely to get pregnant each cycle than younger women, and a part of the reason is the decline in ovarian reserve – the ovary’s ability to mature and release good-quality eggs at ovulation. To support ovarian health and healthy eggs, consider adding DHEA, CoQ10 and B vitamins to your preconception supplement routine.






B vitamins

  • B vitamins like Vitamin B6, B12 and folate have been suggested as potentially supportive of normal ovulation and healthy eggs. For example, an analysis of women included in the Nurse’s Health Study II found that women who consistently took multivitamins containing B vitamins were more likely to have normal ovulation than those who didn’t.
  • B vitamins have other key roles to play in the preconception and prenatal periods. Make sure your prenatal vitamins deliver those in meaningful doses.


4. Support brain development and cognitive health

We are including this last section, not because women over 35 are at a particularly higher risk of being deficient on the particular nutrients that support the baby’s brain development and cognitive health. Rather, we are including it because 1) supporting brain development and preventing neural tube defects is such a crucial aspect of prenatal nutrition; and 2) a vast majority of women, not just those of us over 35, are not getting adequate amount of one key nutrient: Choline.





  • Folate is one of the most important nutrient during early pregnancy. Like choline, it supports the healthy development of central nervous system in the baby. When incorporated into an overall healthy diet, folate can prevent neural tube defects – one of the most common, serious but preventable birth defects.
  • Doctors recommend at least 400 mcg per day.
  • Women with a few common variations of MTHFR gene may have a harder time converting the synthetic folic acid into active folate. If you have these MTHFR variants, opt for prenatal vitamins that use methylfolate, rather than folic acid, so that your body doesn’t have to do the conversion before the body can use it.



  • Omega-3 fatty acids include animal-derived fats like DHA and EPA, as well as plant-derived ALA. As a group, omega-3 fats have been suggested as another key to baby’s healthy brain development and cognitive health even after birth.
  • During pregnancy, make sure to get 1.4 grams of omega-3 fatty acids per day, though some doctors recommend higher amounts to support specific aspects of your health. The requirement drops slightly when nursing, to 1.3 grams.
  • Outright deficiencies of omega-3 is uncommon in the United States, as there are plenty of food sources of DHA, EPA and ALA. For example, a 3-oz portion of salmon provides 1.24 grams of DHA, almost enough to cover your entire day’s need.
  • Some prenatal vitamins contain omega-3 fatty acids. As omega-3 can degrade quickly when stored close together with some of the ingredients in prenatal vitamins, it may be a good idea to take prenatal vitamins without omega-3, and add a separate omega-3 supplement if you are concerned about not getting enough.


Preparing for a pregnancy after 35

The term "advanced maternal age," applied to women who are over 35 during pregnancy, sounds archaic, but there are some valid reasons we should be a bit more vigilant about preconception nutrition after 35. Follow the recommendations from your doctor and/or dietitian to prepare for a healthy pregnancy and a thriving baby - and support your own health and wellbeing.

A good-quality prenatal vitamins that cover the bases can be a great foundation of your preconception and prenatal nutrition. Please reach out with any questions. We are with you.


Ovaterra provides reproductive health resources for general, educational purposes only. This content is not intended to replace medical advice from a qualified healthcare professional.


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