Weighing In On Underweight Pregnancy: What Risks You and Baby Face and How to Handle It

Some women will be skinny before they get pregnant and stay relatively small and trim during pregnancy. Others will be overweight before it. And still, others will gain plenty of weight during those 9 months. Your goal as a mom-to-be is to have the healthiest pregnancy possible, which involves taking good care of yourself for your baby.

With my first daughter, I really let loose. I enjoyed eating and indulging in my cravings. I was living abroad, and friends would send care packages of foods I hadn’t seen in years because it wasn’t available in China. My husband would spoil me by taking me out to Pizza Hut (which, oddly, is a bit fancy over there). It wasn’t until my OB/GYN said in her halting English that I’d better watch out or that baby would come early.

“You’re too big.”

Oh, but it was too late. I was a month away from the big day, and my doctor totally called it. Two weeks before my estimated delivery date, I went into labor. You can read all about that here.

For my second daughter, I was wiser. I kept up with being active, and I watched what I ate. My only problem was my well-meaning mother-in-law who, bless her heart, over-salted everything. It wasn’t until my doctor ordered my husband to keep salt out of my food that she curbed her salt spree.

So, I’ve had two different experiences – one where I gained too much and the other where I gained about the right amount, where I really should have gained just a tad more toward the end. In fact, I remember my doctor telling my husband that this time, he should get me some more pizza and ice cream so I could keep that baby healthy instead of telling me to stop eating so much.

What did I learn?

Baby always comes first. There’s something to be said for overindulging too much and not eating enough, whatever your reasons are. Being overweight isn’t good either (we’ll talk about that further down), but being underweight can be even more dangerous.

What Exactly is Underweight Pregnancy?

As you likely know, we’re all different heights and sizes. There is no one magical weight number you should be at. There’s a range that is healthy for you; only your doctor can assess you and tell you what’s best.

One thing your doctor will do is check your BMI. It calculates your height and weight to see if that’s at a healthy range. A BMI less than 18.5 indicates you’re underweight. You want to aim for 18.5 to 24.9 which is considered healthy. If your doctor tells you it’s 25 to 29.9, you’re considered overweight. Anything above that is considered obese.

What could happen if I have an underweight pregnancy?

Thin Pregnancy

An underweight pregnancy can affect you and your baby in many ways. It’s not a hard and fast rule, but one of your biggest concerns should you not weigh enough is that your risk for miscarriage increases. I don’t want to scare you, but if your doctor says your BMI ranks you underweight, take every step possible to reach a healthy weight. Your doctor will help you, and I have some information for you below, so keep reading.

Another thing that could come into play if you’re underweight during pregnancy is the possibility of premature birth. I’m not talking 2 weeks early like I had. I’m talking about your baby being born before they can fully develop, meaning they’d spend time in the NICU.

Note that:

Gastroschisis is a birth condition that can arise from you not gaining enough weight while pregnant. It’s a fancy word to say your baby will be born with his intestines outside his body, requiring immediate surgery. The CDC says it’s most common in younger mothers who tend to weigh less.

If you’re underweight, your doctor will closely monitor you during your pregnancy to ensure you hit healthy numbers. Planning on starting a family but are on the thin side? It might help you to learn your BMI now to see what you can do to get your body ready.

What causes low BMI?

Being underweight, there are quite a few things that may contribute to it. If you see yourself in any of these, you must discuss it with your doctor, not just for your health but for your baby’s health too.

Low BMI is often caused by:

  • Overdoing it with exercise and not replenishing with enough food
  • Medical conditions like an overactive thyroid
  • Loss of appetite from stress, anxiety, or worry
  • Lack of money for adequate food
  • Eating disorders

Can I talk to you about eating disorders, please? From one mom to another.

If you have an eating disorder, please get help right away. There is no judgment, only love for you. When I was in my teens, I had trouble with anorexia. I thought I was fat. I was anything but fat! My dad is a doctor, so he noticed and got me help. But I really didn’t realize the gravity of the whole situation until about 5 years later.

I looked at photos of myself with an old friend taken during that time frame, and I was shocked. I was too thin! I never realized I was that skinny. It hit me like a ton of bricks. 🙁

Please, please love yourself as much as everyone else does and get help. You don’t have to suffer from a bad relationship with food. Reaching out is the first step. Get the help you need so your baby can have the chance to love you too.

I also want to talk about something else that can affect your weight, either by adding too much or not enough, which is mental health. It’s said that up to 1 in 5 women will have mental health problems at some point while pregnant or in the first year of the baby’s life. If you have a history of depression or anxiety before getting pregnant, tell your doctor.

If you get down in the doldrums for more than 2 weeks and it’s a new thing for you, make sure you speak to your doctor about it too. Those pregnancy hormones can really make things feel uneven and off.

How Can I Gain Enough Weight for My Pregnancy?

Working with your doctor, you’ll want to add more weight if your BMI is low. That doesn’t mean ordering 10 large pizzas per meal or sitting at your favorite buffet restaurant for hours. Empty calories don’t do you or your baby any good. Make the food you eat nourishing and full of goodness.

Here are some suggestions for gaining weight during pregnancy:

  • Switch up to eating 5 or 6 small meals each day.
  • Snack more with nuts, cheese, ice cream, or yogurt.
  • Put peanut butter on other healthy items for added calories.
  • Add more to your meals, like sour cream or cheese.
  • Eat avocado toast. Like you needed an excuse!
  • Choose more pasta, beans, and whole grains.
  • Fill up on good fats (more avocado again, and fatty fish and nuts too).

Now we talked about what to eat to get you to pack on some much-needed healthy weight, but what if you started at a normal weight and fell into a heavier one? Or you were heavy, to begin with, and now you’re in the danger zone.

Now what?

Likely what will happen is what happened during my first pregnancy. My doctor told me to ease up. She recommended I make healthier choices. I should have listened. I was very big by the time I delivered. But during pregnancy, you shouldn’t be losing weight. You’ll have to wait it out until after you give birth. It’s generally not a safe thing to do while you’re pregnant.

If you’re on the wrong track right now, you can still take steps to slow down your weight gain and get into healthy weight management. Here’s what you should try!

Choose smarter when eating out

I get it, believe me. Sometimes you have to pull through the drive-thru, or you’re out to eat. Always make the healthiest choice you can wherever you are. For example, opt for grilled or broiled chicken sandwiches. See if you can replace the bun with a whole-grain option. Get a side salad. Don’t order anything fried. Indulging that craving for fries is great once in a while, but be honest with yourself…if you eat fries at least once a week, it’s way too much.

Choose the right milk

Milk products are great for your bones and your baby’s development inside you. That said, make the switch to 2%, 1%, or skim milk to cut your calories.

Don’t drink sugary calories

Except for milk and a very limited amount of fresh-squeezed, natural juices, skip any sweetened drinks. Sodas, sweet tea, and lemonade are some examples. You’re permitted a little coffee daily but don’t blow it by adding tons of sugar and creamer.

Say no to salt

As I mentioned, my mother-in-law’s salty creations were causing me some problems. Use fresh herbs when cooking instead to give more flavor without making you retain water.

Plan your sweets

You’re pregnant, and I know you suddenly had a crippling craving for s’mores on top of ice cream on top of the cake. I feel you. But (my famous ‘but’ of course!) you can’t eat like that every day. Keep snacks that help you fake it ‘til you make it around the house, and save that crazy dessert for your birthday dinner instead.

I wanted milkshakes during my pregnancy. 😀

In China, they’re not as easy to find. So I would make my own version using bananas and skim milk. I’d sprinkled a little cinnamon and a couple of drops of vanilla extract and blended away. It was thick, creamy, and hit the spot. Plus, it was nutritious. Find ways of tricking yourself into satisfying those cravings the right way; it really does help.

Don’t forget to exercise

If you’re overweight, keeping a healthy pregnancy weight can be much easier if you’re active. As long as your doctor hasn’t ordered you on bed rest for a high-risk condition, you should exercise daily.

Pregnant woman exercise

Exercise is great for burning calories and preparing your body for labor, a very strenuous activity. The more primed your body is, the easier it should be to deliver. Walking and swimming are 2 wonderful ways to get your exercise in. Your doctor can also recommend more based on your fitness level. Generally speaking, if you’re new to exercise, walking and swimming are gentle enough.

For those of you that are fit and may borderline on the low BMI side of things, it’s important to keep active BUT get those extra calories in to help you gain the right amount of weight healthily.

Bottom Line

Your healthy weight is so important during pregnancy. Try to be in that sweet spot. If you’re not, follow these tips and work with your doctor to get there. Too much or too little weight is not good during this time.

You’re beautiful the way you are! It’s hard to accept our bodies when pregnant, but remember what an amazing thing it’s doing. Plus, know that you can get back into great shape after. It will take time, maybe more time than it did at other points in your life, but right now, that baby is more important than your skinny jeans.

Take care of both of you!

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