Postdates Pregnancies and the Biophysical Profile

December 24th, 2010 § 0 comments

A mother’s due date has come and gone.

A few days? “Not a problem.” Such is life, especially with first-time mothers who, on the average, carry their babies for 41 weeks and 1 day.

A week? “It may not be a big problem—due dates are only estimates, after all—as long as the baby is still kicking and active and growing, everything is probably fine.” We will make sure the mother is well-hydrated, and that she is continuing to eat plenty of nutritious foods to ensure the placenta and baby are well-supported and supplied. Also, we will have the mother monitor the baby’s activity a little more closely than before. Did this mother carry longer with any previous babies, or did her mother tend to carry late, too? Sometimes this sort of thing runs in the family.

Two weeks? Hmm…why is this baby not here? Concern starts to build…especially if “dates” are quite certain (based on ovulation chart or date of conception, which are more reliable than LMP or late/mid-pregnancy sonogram). We need to make sure all is still well with baby.

Midwives do not like inducing labor. We are advocates for the natural process, we are the “guardians of natural birth”, we only intervene when truly necessary for the mother and baby’s health and wellness. And then we are fine with intervening, but even then, interventions have risks.

Therein lies my dilemma. I have, during my recent studies, come across numerous articles, and several research studies that have demonstrated that ultrasound has not been proven safe for small bodies and brains, and showing actual harm it can do. So I believe it should be used only if truly necessary, or if the mother decides, after being fully informed, that she wants one done (although I wouldn’t really encourage it without a medical indication, if she wants one, it is her choice). The question then becomes, “What constitutes a truly necessary situation, or a truly good reason?”

Of course, we never used biophysical profiles in years gone by for post-dates mothers—the midwife or doctor would have the mother do kick-counts, and if the baby stayed active, continued growing, and the amniotic fluid felt normal in quantity, it was presumed/assumed that the baby was doing well. (In the absence of any concerning signs, presume that everything is fine, but be watchful.)

We began teaching our clients how to challenge and count the kicks of their babies [fetal kick counts] (FKC) and report any decrease in movement. …Women so often feel incapable of trusting their knowledge of whether their unborn child is doing well. There are many “old wives tales” that tell a pregnant woman that if her baby is still active, delivery is way off or that the baby will stop kicking before she goes into labor. I have used FKC to empower women and give them something they can do to truly monitor their babies’ well-being. I love FKC as a teaching tool. If a baby is not moving, it needs to be assessed right away. Babies even move during contractions. Over the years, I have found that women really only use this means of monitoring if they are worried that the little one is moving less than usual. Drinking a cold glass of water usually remedies the problem and offers the reassurance these women need.

When I first began my practice in this rural community, I worked with a physician who insisted, “Mother Nature knows what she’s doing.” I watched one woman go four weeks past her very certain due date. I watched another go six weeks past the day we were certain she was due. I was a wreck. But my mentor was more than right. Mother Nature does know what she’s doing. Women’s bodies are meant to be pregnant and give birth. Babies have their own time to be born. Pushing women to deliver by 39 weeks is defensive medicine to the level of absurd. Not every baby is ready to be born in that timing.

— Kathryn Jensen excerpted from “Does Mother Nature Really Make Mistakes?” Midwifery Today Issue 72

Now with the advent of sonography, the collective decision made by the by-and-large medical community was that sonograms would do a better job of determining if the baby was doing well than careful palpation and observation/noting of fetal movements. Are they right?

The risk of fetal demise rises as the time past a mother’s due date increases, more so after 43 weeks (although it is rather rare for mothers to carry this late, it can and does occasionally happen). I’d rather be overly cautious than overconfident of the safety of ultrasound and later regret unnecessarily exposing women and their babies to an unproven technology. X-rays were once also thought safe for use during pregnancy on mothers and babies. Only later did we realize that they caused/contributed to childhood cancer. I believe there are good and valid reasons to recommend a sonogram—however, I’m also willing to entertain the thought that perhaps there are lower-tech ways of determining the baby’s well-being in the post-dates period without one.

At this point, I’m most comfortable with doing a BPP (biophysical profile) if a mother goes a couple weeks past her due date, but I’m definitely going to keep studying this issue, and if I find evidence that doing the BPP doesn’t improve outcomes, or no more than having the mother do kick-counts, listening to fetal heart tones for reactivity and palpating for fetal growth, movement, and fluid levels, then I will certainly present that information to my clients if they find themselves carrying post-dates.

Elizabeth Davis in her book Heart and Hands, A Midwife’s Guide To Pregnancy and Birth, has the following to say:

“Can the midwife’s assessments as cited earlier provide enough information to substitute for the biophysical profile? In my opinion, the answer is yes. Although fetal breathing movements [something that is accessed when a biophysical profile is done] cannot be assessed directly, these may be presumed to be adequate on the basis of normal muscle tone, as demonstrated by kick-counts. NST [non-stress test, a test done by monitoring the baby’s heart rate and pattern for a period of time] is readily accomplished with a standard fetascope. And to reiterate, even the subtlest changes in amniotic fluid volume are easily noted with continuity of care [having the same care provider palpate at each prenatal visit].”

And just to clarify, performing a NST with a fetoscope would be more accurately termed an Asucultated Acceleration Test (Varney’s Midwifery, 635).

For further reading:

Suspect Diagnoses Come With Biophysical Profiling
by Gloria LeMay
Postdates Pregnancies from a Midwifery Today E-Issue
A Timely Birth by Gail Hart

Heart and Hands by Elizabeth Davis, pages 86-88, “Postdatism”

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