Prenatal vitamins are designed to support both the health of the mother and the development of the baby during pregnancy. Pregnancy is difficult to predict; it may take a woman 1 month, 1 year, or longer of trying to conceive before she becomes pregnant. Additionally, many critical fetal developments occur before a woman even knows that she is pregnant.1 The results of a 2016 study found that in 2011, nearly half (45%) of pregnancies were unplanned, with a rate of unintended pregnancy among women of reproductive age of 4.5%.2

WHEN SHOULD A PRENATAL VITAMIN BE STARTED?
Because of the prevalence of unintended pregnancy as well as the uncertainty of how quickly or slowly conception will occur, prenatal vitamins should be started 3 months prior to attempted conception.1 This is to ensure that any potential nutritional deficiencies have been corrected, or increased needs supplied, prior to conception.1 If prenatal vitamins cannot be started 3 months in advance, folic acid supplementation should be initiated at least 1 month before trying to get pregnant. This is crucial because folic acid aids in growth and development and because the neural tube, which later develops into the baby’s spinal cord, spine, brain, and skull, forms between week 4 and week 6 of gestation, before most women know they are pregnant. This can help reduce the risk of neural tube defects.3,4 Prenatal vitamins should be continued throughout the entire pregnancy.4

The results of a 2017 survey by the March of Dimes found that only 34% of women aged 18 to 45 years who took a prenatal vitamin during their current or last pregnancy started the prenatal vitamin before they knew that they were pregnant. Although 97% took a prenatal vitamin, these may have not been started by the optimal time to prevent birth defects, which have an annual prevalence in the United States of 120,000, or 3% of births per year. Use of prenatal vitamins prior to the knowledge of pregnancy was lower in minority populations, with just 10% of African American and 27% of Hispanic patients taking them before they knew they were pregnant.5

WHAT VITAMINS SHOULD PREGNANT PATIENTS TAKE?
The American College of Obstetricians and Gynecologists (ACOG) recommends that all female patients of childbearing potential “be screened regarding their diet and vitamin supplements to ensure they are meeting recommended daily allowances for calcium, iron, vitamin A, vitamin B6 [pyridoxine], vitamin B12 [cobalamin], vitamin D, and other nutrients.”6 Folic acid supplementation should be encouraged for these patients as well regardless of dietary intake of folic acid, to reduce the risk of neural tube defects.7

Despite being recommended in 1998 by the National Academy of Medicine as an essential nutrient,8 the role of choline in maternal and fetal development remains underrecognized. Of the top 25 prenatal vitamins, none contained the 450-mg recommended daily allowance, often providing only 0 mg to 55 mg per day.9-11 Lack of sufficient levels provided in prenatal vitamins could be of consequence because only 25% of women of childbearing potential from high-income countries such as the United States obtain enough choline from their diets.10-13 Choline is emerging as a nutrient of important consequence during pregnancy because it plays an important role in neural tube development, memory development, stem cell proliferation, and apoptosis.9 Choline is thought to have an impact on the risk of development of neural tube defects independent of folic acid intake.

The table includes information from ACOG, CDC, FDA, and the World Health Organization (WHO) regarding the recommended vitamins and minerals a woman should take during pregnancy.7,14-19





WHEN CAN A PRENATAL VITAMIN BE STOPPED?
Patients who are pregnant may struggle with long-term adherence to their prenatal vitamin because of undesirable effects such as a fishy aftertaste20 due to docosahexaenoic acid (DHA), constipation from iron or calcium, or general nausea from taking the prenatal vitamin on an empty stomach. Thus, there is a delicate balance between advising women of proper duration of use for health benefits for the mother and baby and preventing unnecessary supplementation due to adverse effects that can affect patients’ quality of life.21

Breastfeeding is well established as the best nutrition option for infants if mothers are able to breastfeed. One of the values of breastfeeding is provision of essential vitamins and nutrients in breast milk. However, it is debated whether simply following a well-balanced diet may be sufficient to provide these valuable nutrients to infants.22,23 The CDC recommends continuation of nutrient supplementation in mothers who breastfeed only if they follow restrictive diets (eg, vegetarian diets). They do state that nutritional supplementation may also offer benefit in women who breastfeed who consume balanced diets.22,23 Supplementation likely provides the greatest benefit to meet increased iodine needs.22 No leading organization provides any clear or specific vitamin or nutrition supplement recommendations in lactation.

Most women will continue the same prenatal vitamin used throughout pregnancy during lactation, but there are different and unique nutritional needs during pregnancy.23 ACOG makes no definitive recommendation on how long prenatal supplements should be continued during the postnatal period or which vitamins should be supplemented and at what dose.24 Supplementation with DHA, vitamin D, folic acid, or iodine has been shown to improve the infant’s visual acuity, hand/eye coordination, attention, problem solving, and information processing.25 The WHO recommends continuation of prenatal vitamins for at least 3 months in the postpartum period in geographic regions with a high incidence (>40%) of anemia in pregnancy.26 It is recommended to increase choline intake to 550 mg daily during lactation.12 Continuation of prenatal supplements until the mother has completed breastfeeding may be worthwhile if the supplement is tolerable and affordable for the mother in light of these data.

KEY POINTS FOR PHARMACISTS
Pharmacists can play a key role in ensuring that patients are taking appropriate prenatal and postnatal supplements—including ensuring that patients are taking formulations that include the vitamins and nutrients recommended by leading organizations at appropriate dosages. Pharmacists can screen both women using contraception and women who are actively planning to try to get pregnant for potential supplementation needs by asking, “Are you planning to become pregnant in the next 12 months?” This allows prepregnancy planning to occur to ensure that patients can try to prevent adverse health outcomes associated with pregnancy and potential birth defects before they occur. At a minimum, all female patients of reproductive potential should be advised to take folic acid, even if adherent to contraception, to reduce the risk of neural tube defects.

Selecting a prenatal vitamin can be an overwhelming task for patients, as nutrient contents vary greatly from one prenatal vitamin to the next and especially because there are no nutrient standards or requirements that must be adhered to for a product to be labeled a prenatal vitamin. Prenatal vitamins that contain appropriate appointments of folic acid, iron, and iodine should be targeted, and these will often contain adequate amounts of other important nutrients such as B vitamins, calcium, copper, DHA, vitamin A, vitamin D, vitamin E, and zinc.27 In their 2018 study, DeSalvo and colleagues found that of the 163 OTC and 88 prescription prenatal vitamins included in the study, more than 80% were able to correct vitamin and mineral deficiencies in the average pregnant woman who could not get those vitamins and minerals from dietary intake alone.28 Generally, these vitamins contained recommended daily allowances for most vitamins and minerals; however, choline, magnesium, and vitamin D were often not provided in sufficient levels.28 Pharmacists should pay attention to the selection of prenatal vitamins and ensure that they include the recommended daily allowance for these vitamins and minerals. Alternatively, they may need to recommend supplementation with an additional supplement to meet these levels. 
 
CORTNEY MOSPAN, PHARMD, BCACP, BCGP, is an assistant professor of pharmacy at the Wingate University Levine College of Health Sciences in Wingate, North Carolina, and a clinical pharmacist practitioner at the Novant Health Arboretum Family & Sports Medicine/Internal Medicine in Charlotte, North Carolina.


REFERENCES
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