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THE HARVARD MEDICAL SCHOOL GUIDE TO Healthy Eating During Pregnancy
By W. Allan Walker, Courtney Humphries
The McGraw-Hill Companies, Inc.Copyright © 2006The President and Fellows of Harvard College
All rights reserved.
How to Prepare for Pregnancy
About half of all pregnancies in the United States are unplanned. But increasingly women are able to plan their pregnancies, a trend that has the potential to improve children's health when mothers-to-be take the time to make sure they are entering pregnancy prepared. If you've started to read this book before pregnancy, congratulations; you have the opportunity to take some positive steps to help secure your future baby's health.
Women who are hoping to become pregnant are often concerned with ensuring their fertility, and we'll talk about the role nutrition may play helping you conceive. The goal of planning for pregnancy is not just to help you get pregnant but also to help ensure that you are in the best possible health when you become pregnant. By achieving a good state of health before your pregnancy, you can help avoid some potential complications and also increase the chances that your child will be healthy. Here are a few of the advantages of prepregnancy planning:
* Reaching a healthy weight before pregnancy will make your pregnancy easier and can contribute to the long-term health of your child.
* Supplementing your diet with folic acid now can help prevent birth defects.
* Adopting good health habits now will help you maintain them throughout your pregnancy.
* Getting any medical conditions under control before pregnancy can help prevent complications.
If you are planning a pregnancy, you should start changing habits now rather than waiting until you are pregnant. There are two reasons why it's good to plan ahead. One is simply that changing habits can be a difficult task. The more time you allow yourself to start following a healthier diet, cutting back on harmful habits, and addressing your own health, the easier it will be to have a healthy pregnancy.
The second reason is the unpredictability of pregnancy. Once you start trying to get pregnant, you won't know whether it will happen this week, this month, or this year. You won't know for sure that you are pregnant until you miss a period and have a positive pregnancy test. By that time, you will probably have been pregnant for a couple of weeks or more. While a few weeks is just a small amount of time in a person's life, it is a critical time for your baby's development. Those first weeks are a time when the foundations of a baby's body are put into place; just three days after your first missed period, all of the major organs in your baby's body have begun to form. During this time, your baby's health is sensitive to potential nutri-ent deficiencies or exposures to harmful substances. Because you can't be sure when pregnancy will happen, the best chance to give your baby a healthy start is to make sure you are already providing the proper environment for a fetus before you become pregnant.
Reach a Healthy Weight Before Pregnancy
Weight plays an important role in a healthy pregnancy. Women whose weight is below normal for their height are at a greater risk for premature delivery and having a smaller-than-average baby. Overweight or obese women are at higher risk for having complications during pregnancy, a difficult delivery, and a baby who weighs more than average—and their babies are more likely to have weight problems as adults. As I will explain further in Chapter 3, both of these extremes can lead to stunted growth and development in the womb. Babies who experience growth restriction in the womb have higher risks of developing chronic disease as adults. So an unhealthy weight isn't just a threat to your pregnancy—it is a factor that can influence your child's health into adulthood.
We often have subjective ideas of how much weight is too little or too much. To get a more objective view, find your body mass index (BMI) in the chart provided in Chapter 7. Body mass index is a ratio of weight to height, and it is commonly used in the health field as a more accurate measurement of body size than weight alone. (After all, a man who is six feet four inches tall and weighs two hundred pounds is not overweight, but a man of the same weight who is five feet seven inches tall is overweight.)
The health consequences of being overweight come from being overfat. BMI is not a perfect measurement because it doesn't tell you if the weight you carry is largely muscle or fat. Many bodybuilders fall into the category of overweight even though they may have very little fat, and just because their BMI is high doesn't mean they will be saddled with the same health problems that come with obesity. However, when most of us gain weight it's because we put on excess fat. So BMI is a useful measure of whether your weight is normal or is putting you at risk for health problems.
There are ongoing debates about what BMI is considered normal, overweight, or obese. In general, people agree that a BMI below 26 for women who are planning a pregnancy is a healthy weight, a BMI from 26 to 29 is overweight, and a BMI above 29 is considered obese. Table 1.1 represents the current classifications agreed on by the Institute of Medicine based on the best evidence about healthy weight.
The specific cutoffs of these categories make it easier for researchers and healthcare workers to classify people and make guidelines, but they can also be misleading. In reality, the health consequences of weight form a spectrum, with potential health risks at either end. People who fall outside the normal range can greatly improve both their chances of conceiving and the health of their pregnancy by reaching a normal weight—or closer to a normal weight—before they begin trying to conceive. If you fall outside a normal BMI, talk to your doctor to see whether it is appropriate to set up a plan for gaining or losing weight before pregnancy to get closer to normal.
It's generally easier for women to gain than to lose, but gaining weight can be a challenge for women who are underweight from severe dieting, eating disorders, or a highly athletic lifestyle. As I'll discuss in the later section on fertility, gaining some weight can also help you conceive in the first place. Your calorie needs grow during pregnancy, and if you have trouble maintaining a healthy weight now, it may be difficult for you to gain the weight you need to throughout pregnancy, especially if you also experience nausea, vomiting, or aversions to certain foods. Don't think about the weight gain itself as the goal; instead, think about gradually increasing the amount of nourishing foods you eat and, if you are an athlete, moderating your exercise levels so you are not expending more energy than you take in. If you have an eating disorder or believe you may have one, seek counseling or treatment in preparation for pregnancy. The undue emphasis our society places on thinness can make it psychologically difficult for many women to gain the weight they need to support a pregnancy, but doing so is critical for your child's health.
Overweight and Obese Women
Weighing too much isn't just a cosmetic problem. Being overweight or obese can lead to serious long-term health problems, including diabetes, heart disease, stroke, gallstones, respiratory problems, and arthritis. In women, obesity can lead to abnormal periods and infertility. Obese women account for one-third of all pregnancies in the United States, and being obese puts women at a higher risk of pregnancy complications such as gestational diabetes, high blood pressure, a difficult labor, or cesarean section. Obese women give birth to larger babies that are more prone to developing diabetes, obesity, and
Excerpted from THE HARVARD MEDICAL SCHOOL GUIDE TO Healthy Eating During Pregnancy by W. Allan Walker. Copyright © 2006 by The President and Fellows of Harvard College. Excerpted by permission of The McGraw-Hill Companies, Inc..
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