Too Much Water in the Pool

How much is too much?


Kirsa wrote last week with questions and confusion. Her OB told her that her baby measured small for dates and she needed an ultrasound and maybe an induction. She's due this month and has been healthy throughout her pregnancy—no diabetes, normal screening exams, no specific health concerns. The ultrasound technician told her that no, the baby wasn't small. As a matter of fact, it was rather large for dates. She got a call from her OB the next day saying that since she had a big baby after all and also had more than the normal amount of amniotic fluid, she should be induced a few weeks early. Kirsa's a little confused. Is her baby too small or too large? What's the deal with too much amniotic fluid? Does her doctor just want an induction? She also tested positive for group Beta Strep and her doctor told her she'd need antibiotics in labor to avoid infecting her baby. Kirsa hoped to avoid an induction, epidural and all the monitoring that goes along with that when delivering in the hospital. Now she wonders what to think.

I'm going to talk about amniotic fluid this week and we'll cover Group Beta Strep next week. Kirsa had never heard of polyhydramnios (too much amniotic fluid). I'm not surprised. It only happens in about 2% of all pregnancies and most of the time it presents no real problems. Polyhydramnios is diagnosed by ultrasound. Technicians look for pockets of amniotic fluid and measure them. This test is called an Amniotic Fluid Index (AFI) and has a normal range of 8-18 cm of fluid. That's about a liter. An AFI less than 8 is called olioghydramnios and above 18, polyhydramnios. Kirsa says her AFI was 26. Yep, that's a little high. But what the heck does it mean?

Amniotic fluid starts developing at about the 12th day after conception. For approximately the first 12 weeks the fluid is supplied by Mom. After that, it's made up primarily of fluid the baby swallows and pees out. Yep, amniotic fluid is largely made up of baby pee. It's just all so glamorous, isn't it? Amniotic fluid serves a lot of purposes. It gives the baby a pool to swim in, move around in and exercise his growing muscles. It filters through the lungs and digestive system as baby breathes in and swallows the fluid. It's sterile and healthy and chock full of good stuff that baby needs. That's why we obsess over leaks in the water bag, too much or too little fluid. There's hardly a woman alive who hasn't given some thought to what it would be like to break their water bag in a crowd of people. We've got water on the brain.

The concerns about polyhydramnios are that maybe baby's digestive system or kidneys aren't functioning correctly to regulate fluid levels. There's also a higher incidence of polyhydramnios in babies with genetic anomalies like Downs Syndrome and heart defects. Women with diabetes have more poly too. Some women go into premature labor because the amniotic sac can't hold all that water and it breaks early. Once in a while, babies get tangled up in their umbilical cord because they can move too freely with all that fluid. If the tangle turns into a knot or wraps too tightly around baby's neck or body—that can be a tragedy. There's a risk of placental abruption (the placenta separates from the uterus too soon). There's about a 0.4% chance of stillbirth with poly. Women with normal fluid levels have about a 0.2% chance. A big worry is with all that water in there, the umbilical cord has a lot of room to roam and might get in the way when the water breaks. These things happen rarely but the risks are real. Most of the time, polyhydramnios simply means we need more towels to sop up the mess when the water bag breaks.

Kirsa said she didn't have diabetes so we can rule that out. All of her genetic screening exams and ultrasounds showed a normal baby. She's close to her due date so we can quit worrying about premature labor and premature rupture of membranes. So why does her doctor want to induce her?

It's a matter of control. Whenever a water bag breaks, there's a chance the umbilical cord will slip out of the cervix in front of the baby's head, get compressed and essentially cut off blood supply to the baby. This is bad, folks. We hate when this happens. It always means a mad dash for the operating room and a cesarean section STAT. Kirsa's doctor wants to deliver her in a controlled environment so that when the water bag breaks, medical personnel will be there ready to save the day, if the cord comes out first.

Kirsa doesn't really want to be induced though. What are her options? She can ask for regular nonstress tests to establish baby's wellbeing. That means she gets hooked up to a fetal heart monitor for a short time (usually less than an hour) and nurses (or her doctor) look for signs that baby's heart beat looks fine. She can ask for another ultrasound to see if baby's fluid level is increasing, decreasing or staying as is. She can also tell her doctor that she just wants to wait and see what happens. She's got choices.

Though there's a very small chance her amniotic fluid will cause trouble, there's a very big chance it won't. It's hard to take chances when baby's health is concerned and that's probably why her doctor is pushing for an induction. Kirsa's a little confused, in part because it seems like just a week before, her doctor was pushing for induction for a small baby. Turns out baby wasn't so small after all. It's possible her doctor just likes induced labors because they're more convenient, controlled and easier on his/her schedule. Kirsa has to weigh these factors and make a decision.

I hope this all turns out to be just a case of a little too much water making a big mess in your labor bed. Next week we'll talk about Kirsa's concerns about Group B Strep. Kirsa, good luck with your birth. Chances are excellent everything's going to turn out just beautifully.

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