Week 21: Weight Gain

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This is your Pea in the Podcast for week 21 of your pregnancy. I'm Bonnie Petrie joined by Dr. Laurie Swaim, an obstetrician with Houston Women's Care Associates in Houston, Texas.

You are now in the second half of your pregnancy and if you had the big anatomy ultrasound recently you're probably still feeling the afterglow of the up-close and personal peek you got of your baby as you take on now, week 21. "Well parents are very excited because they learned that their baby hopefully has normal anatomy. There are a few things on the ultrasound that if not normal, if you didn't have the discussion about that and if you didn't see them on the day of the ultrasound, then there are some things you go over if there are any minor or major abnormalities. Pretty much women can reliably feel babies move by 21 weeks, so they're happy about that. They tend to feel really good. People are starting to realize their pregnant so they smile at them and hold the doors for them yet they're not wobbling around and don't feel really fat."

But Dr. Laurie Swaim says over the next two months or so, that's going to change, a lot. "Between 20 and 30 weeks is when actually the rate of weight gain is the greatest. So I do warn people that the next time they come or more likely the visit after that (I tend to see people every four weeks of gestation as long as they're uncomplicated) and that the next time I see them their weight may have increased to a greater degree than it did between the last visit and this visit." In fact, for many women about half of their total pregnancy weight gain occurs during the next 10 weeks or so. But everybody will not gain the same amount of weight. "Remember either the weight gain for a woman when she's pregnant is really based on her original body mass index. Years ago, I think people used to think a fat baby was a healthy baby so moms were 'you're eating for two kind of thing, pack it on'. Then there was a time I think where women were actually given amphetamines so they wouldn't gain a lot of weight. Although that sounds kind of fun, it doesn't turn out to be a good idea either. But we know that with a woman with an average body mass index we would anticipate a weight gain for a singleton pregnancy of somewhere between 25 and 35 pounds. That's not necessarily amortized evenly over the whole 40 weeks but it's a total weight gain. We know that is the weight gain that is associated with the healthiest outcome for both. But for women who are underweight we expect more, between 35 and 45 pounds. Women who are overweight, somewhere between 15 and 25 pounds but these are just guidelines, we don't beat it off you if you gain too much as long as the baby is growing well and you haven't quite attained, or the women hasn't quite attained that weight then usually things are okay. We do always try and supplement with calcium for example and they're taking a regular vitamin and hopefully their diet is well balanced."

Some women revel in their roundness during pregnancy and enjoy feeling like a fertility godess so the weight gain doesn't bother them. But Dr. Swaim says some women really struggle with watching the numbers on the scale rise. "One of the things which we should be cognizant of is people with a history of eating disorders; it is real problem for them. We talk about beforehand that this isn't about them anymore, it's about the baby. Most are okay, I've actually only had really a handful or less of patients in my entire career that have had such significant eating disorders that they couldn't deal with or wouldn't eat during pregnancy." So what are the risks of not gaining enough weight while pregnant? "The dangers with not putting on enough weight, not eating and drinking enough, are nutrients to the mother. A lot of people don't think about that but osteoporosis, that kind of stuff. Deep vein thrombosis is increased in pregnancy anyway but if you really aren't drinking anything then it's possible there could be fledging, I say that because I actually had a patient who had that happen to her, and wasting away of muscles, etc. For the baby it can be what we call 'intrauterine growth restriction', the term used to be call IUGR or intrauterine growth retardation but that term has been obsolete for a number of years now. That means that the baby would be smaller than the 10th percentile for its gestational age. And why do we care about that; certainly small babies women always have this unfounded hope that small babies don't hurt as much coming out. I think they all hurt coming out, but anyway, because the baby's weight is the best determinate how it will do when it is born, in the nursery, especially if it is premature. Little scrawny babies have more risk to them, they also don't tolerate labor as well, the placentas don't function as well. Another problem of underweight is if the baby's not getting the nutrition, doesn't have its own fat stored, and isn't getting adequate, for example, blood flow through the placenta then it may not make enough urine and it may not have enough fluid and the list sort of goes on and on."

But Dr. Swaim says while the litany of risks associated with not gaining enough weight is long, the list of risks associated with gaining too much weight is as long, if not longer. "Besides the fact that you have to lose it when you're done, and that's both a physical and psychological issue, and for health benefits there's increased risk of diabetes and also of osteoarthritis, heart disease and stroke and all that kind of stuff. There are self image issues; once you have a baby right away, especially your first one, it's not like you feel all that great about your body sometimes. To know that you have 50 pounds to lose as opposed to 30 pounds to lose may make that task more daunting. As far as in the delivery room, it's a big deal. There's a much higher rate of cesarean delivery. In the event that there is a cesarean delivery there's greater risk in them than someone who isn't overweight for wound complications. I'm not just talking about wounds turning red, I'm talking about wounds opening, wound infections, wound hemotomas, wound seromas, wounds that have to be packed for weeks. There's a greater risk for deep vein thrombosis, there's a greater risk for pneumonia, there's a greater risk for trauma to the fetus. There's this myth that we can tell you how much your baby's going to weigh and there's absolutely no way that we can tell you how big your baby is going to be even with ultrasounds there are error rates upwards of 10%. Furthermore, even if we know the size of the baby that doesn't mean we know whether it's going to come out easily or not. What we do know is really big babies, greater than 4500 grams, greater than 10 pounds, are at a greater risk for having birth trauma and we can't predict who that's going to happen to. There's also increased risk of traumatic delivery of the mother with a really big baby, with greater extension of lacerations or episiotomy or what have you. So it's sort of not good to be either, although I have to say most women who are overweight and most women who are underweight have successful deliveries also. Along with the risk of diabetes when you're not pregnant, that risk of gestational diabetes is greater if you're overweight as well." So weight is an important concern while you're pregnant and your doctor or midwife can help you figure out just how much weight you should be gaining and they'll help you manage your weight gain along the way.

Now as you gain weight, some of you will notice an unpleasant change in the skin on your belly, yeah, stretch marks. "It's probably mostly genetic it is who has got what kind of collagen. Everyone pretty much stretches to a similar degree to have a full-term baby and it's true some women get nasty, nasty stretch marks and some women have none. The good news is that they don't stay red forever, they fade to silver and the bad news is there's really nothing you can do to prevent them or to make them go away." So ask your mom if she had stretch marks, if she did there's a good chance you will too and all the cocoa butter in the world won't stop them. But that cocoa butter may ease the itching so put your partner to work rubbing that growing belly.

So what's your baby doing now? Well they're swallowing a lot of amniotic fluid which is absorbed or excreted as urine. The skin cells they ingest are building up in the bowel and they'll become the first bowel movement after birth. Your baby's permanent teeth are forming in their gums. Speaking of fat (we were talking about your fat) called the brown fat that will help your baby stay warm when they're born, it is starting to collect a little in places like the chest and the neck, that is important stuff. Now your little one will not be your chubby cherub for a while yet but they will add fat over the next weeks and months until they're ready to be born in about 19 weeks. That's right, you are 21 weeks pregnant and you are now only 19 weeks away from week 40.

That's your Pea in the Podcast for week 21 of your pregnancy. Dr. Swaim and I look forward to talking to you again next week. Enjoy this week. For a transcript of any of our Pea in the Podcasts go to our website peainthepodcast.com. For Pea in the Podcast, I'm Bonnie Petrie, thanks for listening.