“By the 40th week,” the author writes of her pregnancy, “I had had 11 ultrasound exams...Still, with all that information, we had little clarity about whether anything was wrong.” (iStockphoto)

We arrived for my 38-week ultrasound wondering if this was the day our baby would be born. I showed no signs of early labor, but my obstetrician had suggested inducing if our child’s growth was not progressing well.

Through a series of sonograms, my husband and I had watched our unborn child slip lower and lower on a growth chart. And so I held my breath while sound waves and echoes illustrated what we could not see.

His measurements were still smaller than expected, but his heart rate and movements were reassuring. The doctor sent us home confused.

That night on the phone, my mother listened as I talked through hormone-fueled tears about amniotic fluid levels and growth percentiles. And as usual, she struggled to relate. “We never had this much information,” she said.

We were in the depths of pregnancy paranoia. What once seemed a magical transformation from embryo to newborn has become a nine-month research expedition, thanks to advances in ultrasound screening, prenatal testing and an explosion of Internet sites where expectant parents can explore every nuance of fetal development and every thing that can go wrong.

The information overload is being eagerly consumed by parents with 47-point birth plans who have learned that knowledge is power and who want to be active participants in their care, said Penny Simkin, a Seattle-based childbirth educator who has been helping parents navigate pregnancy and birth since 1968. “Having all that access can be troubling,” though, she said. It’s so hard to “sift through all the information that you get.”

For me, and for many friends approaching parenthood for the first time, the experience often felt more stressful than joyous.

New tools, new fears

Obstetricians are trained to use every available tool to identify potential problems early on and alleviate risk, and new technologies continue to churn out new tools.

Financial incentives for doctors and a fear of litigation help fuel an abundantly cautious approach, experts say. And for many women, there is little disincentive to splurge for more tests when many insurance plans pick up most of the tab, said Katy Backes Kozhimannil, a University of Minnesota professor who studies health-care costs.

Then there’s the added circumspection that comes from making health-care decisions for two.

A large majority of new mothers — 70 percent — reported having had at least three ultrasounds during their pregnancy, according to a national survey released by Childbirth Connection, a nonprofit group. The survey included 2,400 women who gave birth to single babies between July 2011 and June 2012. Nearly a quarter of the women had six or more ultrasounds. And about two-thirds of the respondents said they believe more tests mean better care.

Yet, increased testing can exact an emotional toll, said Aaron Caughey, chair of the Department of Obstetrics and Gynecology at Oregon Health and Science University School of Medicine. Obstetricians rely frequently on non­invasive screening tests with uncertain and sometimes false-positive results, which they feel compelled to affirm or discount through more testing, he said.

These tests, of course, can lead to a diagnosis that may help save a baby’s life or inform a parent’s choice to have an abortion. Often, at least for a while, parents are left to wrestle with a murkier result, and a what-if.

“That’s the trade-off,” Caughey said. “A lot of anxiety for a lot of people to benefit a small number.”

Bliss gives way to anxiety

After half a lifetime of hoping and half a year of actually trying, I had imagined pregnancy to be a happy time. I would learn to make pottery and grow a garden as I took my turn in a rite of passage shared by more than 120 million women every year.

During the first trimester, I was consumed with the weight of a life-changing secret and the fear of miscarriage, not to mention a churning nausea. As a woman of “advanced maternal age” (having reached 35), I was offered a litany of screening tests for birth defects. We learned our child had a 1-in-147,811 chance of having Down syndrome, a 1-in-more-than-250,000 chance of trisomy 18, and a 1-in-119,527 chance of having a ventral wall defect.

A breakthrough came at our 12-week sonogram when we listened to the thwomp-­thwomp sound of a heartbeat and watched the pixelated image as a nose, a round belly and two legs emerged. A baby! The 20-week peek was equally exalting. A boy!

Things improved. My mother visited and we filled the garden with pansies (though paranoia had already crept in: I took care to wear heavy gloves after I read about toxoplasmosis, which is spread by cat feces — we have an outdoor cat — and can cause brain damage in utero). And I found a ceramics studio where I could spend Saturdays (and where I was warned to stay clear of the five-gallon containers of liquid stains that might contain lead.)

But real anxiety took hold during a routine doctor’s visit at the beginning of my third trimester. A simple tape measure showed that my belly was small given the baby’s gestational age, and I was referred for an extra ultrasound. The baby looked okay, but his head in particular was small, the doctor said. Probably nothing. Maybe genetic. “Something to watch,” he said.

Within an hour, my husband and I were typing the words into Google: small head fetus. Microcephaly, we whispered as we pored through dozens of Web sites and chat rooms, then restlessly considered the possibilities.

We were referred to a specialist for high-risk pregnancies, who did not identify any fetal anomalies but suggested we keep monitoring.

Biweekly sonograms turned to weekly sonograms, and the mystery of emerging life dissolved into a series of black-and-white snapshots, none of which eased our worries.

By then I was less entranced by the image on the screen than any flicker of emotion on the sonographer’s face, as she clicked and dragged the mouse to measure the femur, the abdomen, the circumference of my baby’s head.

His movement and muscle tone were consistently good — no surprise to me, based on his frequent kicks and somersaults. But his head dropped from the 10th to the fifth to the third percentile. Perhaps the placenta was failing; perhaps it was nothing, the doctor said.

Under heightened scrutiny, sonograms were turning up different concerns. A few centimeters less amniotic fluid than earlier sonograms had shown led to a call for bed rest — and two more sonograms in eight days.

In the 30th week, something else: The baby’s head was not yet facing down. The doctor suggested we schedule a Caesarean section “in case.” I consulted a doula and a chiropractor and made an appointment for an adjustment, praying that it would help move the baby.

The next week, his head was down.

By the 40th week, at full term, I had had 11 ultrasound exams, for which our insurance was billed more than $9,000. Still, with all that information, we had little clarity about whether anything was wrong.

Some perspective came finally from our pediatrician. As we neared my due date, we went for an introductory visit and described our concerns about the baby’s development.

She listened, then went to get a tape measure and a laptop. After measuring my head, she pulled up a growth chart. I was in the fifth percentile.

A week after my due date, my son was born — a healthy six pounds, 10 ounces and with a smaller-than-average head.

In the months since, during routine visits to the pediatrician when we look at the latest growth curve, I try not to get too concerned when our son is not in the middle.

“Someone has to be in the fifth percentile,” Penny Simkin said to me. “You can thank him for adding to our database.”