Dos and Don'ts in Pregnancy: Truths and Myths
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Clinical Expert Series Dos and Don’ts in Pregnancy Truths and Myths Nathan S. Fox, MD Pregnancy is a time of excitement and anxiety. The reality for pregnant women is that their actions could affect their pregnancies and their fetuses. As such, they need to know what they should and should not do to minimize risk and optimize outcomes. Whereas this advice used to come from doctors, a few books, and some family and friends, in the age of the internet, women are now bombarded with information and recommendations, which are often confusing at best and conflicting at worst. The objective of this review is to present current, evidence-based recommendations for some of the things that pregnant women should and should not routinely do during pregnancy. (Obstet Gynecol 2018;0:1–9) DOI: 10.1097/AOG.0000000000002517 regnant women are bombarded with advice. analysis were not performed for each topic. Rather, PAmong social media, web searches, direct market- quality systematic reviews are referenced (such as ing, family, and friends, it can be difficult for women to a Cochrane review) as are guidelines from several navigate the myriad of conflicting recommendations national or international organizations such as the regarding what they should and should not do when American College of Obstetricians and Gynecologists they are pregnant. This leads to confusion at best and (ACOG). Relevant studies are also referenced to sup- misinformation at worst regarding nearly all facets of port the “bottom line” conclusions of the author life—eating, drinking, sleeping, working, travel, exer- (Box 1). It is of course possible that in certain instan- cise, and sexual intercourse, to name a few. Women ces others could read the same studies and come to usually turn to their prenatal care providers for direc- different conclusions in general or for a specific tion, but health care providers are also exposed to the patient. However, the goal of this article is to combine same variety of opinions regarding routine advice for these topics into one source that can be used as a start- pregnancy. This article is meant to be an evidence- ing point for discussion with pregnant women, and based review of common recommendations for preg- the article itself can be shared with pregnant women nant women. It is not meant to be exhaustive nor is it as well. meant to replace more expansive reviews of each topic. As such, a systematic review and meta- PRENATAL VITAMINS Prenatal vitamins are designed to meet the From the Maternal-Fetal Medicine Associates, PLLC, and the Department of Obstetrics, Gynecology, and Reproductive Science, Icahn School of Medicine at daily mineral and vitamin (micronutrient) require- Mount Sinai, New York, New York. ments of most pregnant women. However, except for Continuing medical education for this article is available at http://links.lww. folic acid and possibly vitamin D and iron, it is com/AOG/B71. unknown whether meeting recommended dietary The author has indicated that he has met the journal’s requirements for author- allowances improves outcomes or whether failing to ship. meet these recommended allowances worsens out- Corresponding author: Nathan S. Fox, MD, 70 East 90th Street, New York, NY comes. Additionally, for women with well-balanced, 10128; email: [email protected]. Financial Disclosure nutritious diets that meet the recommended allow- The author did not report any potential conflicts of interest. ances, supplementation is likely not required. If supplementation is required, there is no known best © 2018 by American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved. formulation. A simple multivitamin will normally ISSN: 0029-7844/18 suffice, including nonprescription vitamins. VOL. 0, NO. 0, MONTH 2018 OBSTETRICS & GYNECOLOGY 1 Copyright Ó by American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. A Cochrane review of randomized trials in low- (m)]2; Table 1).9 These recommendations are sup- and middle-income countries where micronutrient ported by mostly retrospective data showing a direct deficiencies are common found that micronutrient correlation between maternal weight gain and birth supplementation reduced the risk of low birth weight weight. Several observational studies have shown that and small for gestational age, but there were no other weight gain below or above the National Academy of differences in maternal or neonatal outcomes.1 These Medicine recommendations is associated with adverse trials are likely not generalizable to higher income pregnancy outcomes. One recent meta-analysis dem- countries. For this reason, health authorities in the onstrated that weight gain below the National Acad- United Kingdom do not recommend supplementation emy of Medicine recommendations is associated with aside from folic acid in the first trimester and vitamin a higher risk of preterm birth and small-for- D throughout pregnancy. gestational-age newborns; weight gain above the Folic acid deficiency is associated with fetal neural National Academy of Medicine recommendations is tube defects; therefore, women who do not consume associated with a higher risk of macrosomia and cesar- at least 400–800 micrograms of folic acid daily should ean delivery.10 be advised to take folic acid supplementation from Women are also advised to eat an additional 350– prepregnancy until the end of the first trimester.2 450 calories per day in the second and third trimes- Women with a history of a fetal neural tube defect ters. It is unclear whether women need to consume should take 4,000 micrograms (4 mg) daily.2 additional calories in the first trimester. However, Iron supplementation is advised as a result of the these recommendations as well as the baseline caloric risk of maternal anemia at birth.3 However, if dietary requirements are highly dependent on a woman’s iron is adequate (30 mg/d) and anemia is part of rou- activity level, her height and weight, and her own tine prenatal screening (which it usually is in the metabolism history. Therefore, recommendations United States), there is no known benefit to supple- need to be individualized. General dietary recommen- mental iron in the absence of anemia. dations for women should include eating plenty of Vitamin D deficiency is associated with several fruits and vegetables, whole grains, dairy, and a variety adverse outcomes such as preterm birth and pre- of proteins. A good nutrition resource for pregnant eclampsia, but it is currently unknown whether women is a website run by the U.S. Department of supplementation improves outcomes.4–6 The National Agriculture, www.choosemyplate.gov. Academy of Medicine (previously known as the Insti- For women who eat well-balanced diets with tute of Medicine) recommends that all women youn- adequate caloric intake yet have weight gain below ger than 70 years consume 600 international units of or above the National Academy of Medicine recom- vitamin D daily and recommends the same for preg- mendations, it is unknown whether they should nant women.5 Currently, ACOG does not recom- increase or decrease their intake to meet the National mend routine screening for vitamin D deficiency nor Academy of Medicine weight gain recommendations. does it recommend supplementation beyond the dose Because those recommendations were derived from in a standard prenatal vitamin (usually 200–600 inter- observational data, they should be used as a general national units).6 guide and not as an overriding requirement. The recommended daily allowance of calcium for women age 19–50 years is 1,000 mg/d, including dur- ALCOHOL ing pregnancy.5 For women with low calcium intake, High alcohol intake in pregnancy has been associated calcium supplementation has been shown to reduce with fetal malformations and developmental delays, the incidence of hypertensive disorders of pregnancy7 Table 1. National Academy of Medicine* but not the incidence of other adverse outcomes.8 Recommendations for Weight Gain in Therefore, women should be sure to consume Pregnancy through diet or supplements at least 1,000 mg of cal- cium per day. Most multivitamins and prenatal vita- Prepregnancy BMI Category Recommended Weight mins have only approximately 200–300 mg of (kg/m2) Gain (lbs) calcium. Underweight (less than 18.5) 28–40 NUTRITION AND WEIGHT GAIN Normal weight (18.5–24.9) 25–35 Overweight (25.0–29.9) 15–25 The National Academy of Medicine recommends Obese (30 or greater) 11–20 weight gain in pregnancy based on the prepregnancy BMI, body mass index. body mass index (calculated as weight (kg)/[height * Previously known as the Institute of Medicine. 2 Fox Dos and Don’ts in Pregnancy OBSTETRICS & GYNECOLOGY Copyright Ó by American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. Box 1. Dos and Don’ts in Pregnancy Box 1.Dos and Don’ts in Pregnancy (continued) Prenatal Vitamins Fish Consumption (continued) For women who do not achieve this, it is unknown Pregnant women should consume the following whether DHA and n-3 PUFA supplementation are each day through diet or supplements: beneficial, but they are unlikely to be harmful. o Folic acid 400–800 micrograms (until the end of the first trimester) o Iron 30 mg (or be screened for anemia) Raw and Undercooked Fish o Vitamin D 600 international units o Calcium 1,000 mg In line with current recommendations, pregnant Prenatal vitamins are unlikely to be harmful. Therefore, women should generally avoid undercooked fish. they may be used to ensure adequate consumption of However, sushi that was prepared in a clean and several vitamins and minerals in pregnancy. However, reputable establishment is unlikely to pose a risk to their necessity for all pregnant women is uncertain, the pregnancy. especially for women with well-balanced diets. There is no known ideal formulation for a prenatal vitamin.