Category: pregnancy

How could you possibly be pregnant and not know it?

Posted in pregnancy by jenapincott on April 10, 2010

Now at the start of third trimester, I find it inconceivable that there are women at this stage — and beyond — who still do not know they’re pregnant.

Here are the astonishing statistics: 1 in 455 women doesn’t know she’s pregnant until after week twenty, and 1 in 2,500 is oblivious until she actually goes into labor. The latter are known to give birth, without medical assistance and in agonizing pain, in Walmart bathrooms and at proms, in dorm rooms and in their own bathrooms. They had no idea they were pregnant because they had irregular periods, have been on birth control pills, are in perimenopause, have had menstrual-like bleeding, and/or are overweight and less sensitive to weight gain.

But I know what you’re thinking because I’ve thought it too: it’s denial. On some level the ladies must’ve known they were pregnant but couldn’t deal with the reality.

Yet the more I explore the origins of cryptic pregnancy, as the condition is clinically called, I realize that denial or mental illness doesn’t explain most of the cases. Only a minority of cryptic pregnancy cases has been attributed to personality disturbances (8 percent) or schizophrenia (5 percent). It appears that most of these women are perfectly sane, educated, and in stable relationships. Quite simply, they do not know they’re pregnant because they have no symptoms — no weight gain, no nausea, and little to no abdominal swelling. Or the symptoms are so subtle as to be easily mistaken for something else.

Every pregnancy is a tug-of-war of resources between Mom and fetus. Each has her self-interest in mind. Most of the time the tug-of-war ends up in a happy equilibrium. Mom provides enough nutrients, but not too much too handicap herself. But sometimes Mom gets more rope….at the expense of the fetus.

According to evolutionary psychologist Marco Del Giudice this might happen in a few ways. For one, the fetus might not be putting out enough signals that it exists and needs resources. One way fetuses announce their existence is through HCG, the hormone that makes a home pregnancy test turn positive. In many cases, the higher the HCG, the more severe the morning sickness and other symptoms. A baby that produces a scant amount amounts of HCG might go “under the radar,” failing the pregnancy test and going unnoticed by the mother — physiologically and psychologically. This would mean the baby gets fewer resources than she otherwise would. The lack of HCG signaling in cryptic pregnancies explains why these babies are so often born preterm, underweight, and small for their gestational age. They didn’t ask for more resources from Mom, and they didn’t get any.

There are a few reasons why a baby wouldn’t produce enough HCG. One is chromosomal anomalies; that is, the fetus has a birth defect and is in danger of miscarrying. It’s also possible that an otherwise healthy fetus simply puts out low quantities of the hormone due to a genetic quirk.

Or, here’s an interesting theory: Maybe Mom has stress and relationship problems. In this case, biologically speaking, it may be in the fetus’s best interest for the mother to be completely oblivious to the fact that she’s carrying to prevent being rejected and miscarried, which may happen when a woman is stressed. As Del Giudice points out, in our evolutionary past a woman who did not know she was pregnant and had few to no symptoms could conserve precious energy. She would be able to move freely and eat food of any kind, and as a result be better able to survive in the face of stresses and threats. In this case, babies may put out less HCG or stressed-out moms may unconsciously lower their sensitivity to the hormones.

Seen this way, cryptic pregnancy is an adaptive “emergency” mechanism — essentially, the fetus sensing a threat and striking a bargain with the mother by demanding little and laying low. When the normal stresses of pregnancy might otherwise trigger a miscarriage, this “stealth strategy” allows the fetus to survive.

Why pregnant women are calmer

Posted in news, pregnancy by jenapincott on March 30, 2010

If you were to take the Trier Social Stress Test (TSST), as nearly one hundred fifty pregnant women did in a study led by Sonja Entinger at the University of California at Irvine, you’d be led to a windowless room with a video camera and instruments that measure your vital signs. There, an assistant would ask you to sit and be hooked up to instruments that measure your vital signs. In the room you’d also find three men and women sitting at a table, waiting for you.

They are your interview panel.

Facing them belly-on, your instructions are to pretend that you’re applying for a job and must deliver a five-minute speech to convince them that you’re right for the position. Someone would say 1-2-3-GO, and you’d start babbling, hopefully coherently. If you have nothing more to say before your time is up, one of your interviewers will blandly instruct you to continue. Run out of words again and twenty seconds of eerie silence will fill the room. And when you’re finally done, you’ll be asked to do a bit of mental math — say, to count down, in increments of thirteen, from a large prime number like 54,499. Before and afterward the fifteen minute ordeal, a researcher will enter the room and hand you a swab to collect your saliva for testing.

Analyzing all the data from their study, including an analysis of body language and hormone levels of women who took the TSST, the UC Irvine researchers confirmed something remarkable: the further along a woman was in her pregnancy, the less stressful she found the stress test. Compared to their stress levels in second trimester (17 weeks), volunteers in their third trimester (31 weeks) had lower blood pressure, slower heartrates, and lesser spike in the hormone cortisol. Pregnant women also did not stress out as much as nonpregnant controls who took the same tests at the same time intervals. This was not the first study that found that pregnant women, especially those in third trimester, are calmer than nonpregnant women under the same (short and moderately stressful) circumstances. But it was the first time that the same women were tracked at different stages of gestation.

So what is that makes pregnant women more Zen as they approach their due date? The likely answer is that the body reduces the sensitivity of cortisol receptors, even though baseline levels of the stress hormone are higher. In other words, it takes more stress hormones than usual to get the nervous system all hot and bothered. At the same time, the placenta increases production of an enzyme that changes cortisol to an inactive form, meaning that less of the toxic stuff filters through to the baby. Near the end of pregnancy, probably to calm you down before labor and help you bond with the baby, your body also produces more of the nervous-system soothing hormones oxytocin and prolactin.

All this is good news for moms who are slammed with short-term mild to moderate stress late in their pregnancies.

But there’s an even bigger surprise to come out of this. You may think this is your body subconsciously protecting the baby at a time of stress. But it’s just as likely that it works the other way around: your baby protecting you (as well as herself), because her placenta is responsible for at least some of the stress-dampening response to cortisol. It’s a beautiful idea — mother and child soothing one another in the face of life’s assaults.

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