Predicting Your Baby's Sex

Last Editorial Review: 1/31/2005

How well can rings, dreams, or countenance foretell boy or girl? Some people swear by old wives' tales as foolproof methods for pregnancy prognostication.

By Gina Shaw
WebMD Feature

Reviewed By Brunilda Nazario

Grandparents, mothers-in-law, bookstore clerks, the woman in line behind you at the grocery store -- if you're pregnant, everyone wants to guess whether you're going to have a boy or a girl. Many of them claim to have a "foolproof method" to figure out whether you'll be painting the nursery pink or blue.

"A gas station attendant told me I was having a girl because my face looked smiley," recalls literature professor Talia Schaffer, whose first baby, born in May, was indeed a girl. "He said with a boy, the mother's face looked tired! Someone else also predicted a girl because I was carrying low. Lots of people told us their guesses, and weirdly enough, everyone guessed correctly that it was a girl."

Although Schaffer's fortunetellers all proved accurate, that was probably just luck. In a study published in the journal Birth in September 1999, Johns Hopkins School of Public Health researchers asked 104 pregnant women to guess their baby's sex, using whatever method they liked, whether it was hunches, dreams, or rings on a string. The women were right 55% of the time, or about what you could expect from random guesses.

But just to throw a little confusion into the mix, the study also found the mothers-to-be who had the highest levels of education (12 years or more) were far more accurate, predicting their baby's sex correctly 71% of the time. These women most often based their gender predictions on dreams or feelings, and those were the ones that proved most prophetic.

Foolproof Methods?

They're as old as pregnancy itself, these boy-or-girl prognostications, and nurses and midwives have heard them all over the years. Here are a few of the most common -- and the strangest -- old wives' tales:

  • Dangling a ring -- usually her wedding ring -- on a string over the pregnant woman's belly. If it swings back and forth, it's a boy. If it moves in a circle, it's a girl. "The ring over the belly is a biggie," says Tara Voto, RN, BSN, a labor and delivery nurse at St. Barnabas Hospital in Livingston, N.J. "I probably hear that one more than any other."

  • The heartbeat theory. "Fetal heart rates range between 110 and 160," explains Patricia Crane, MSN, CNM, director of the nurse-midwifery service with the University of Michigan Health Systems. "If your baby's heart rate averages in the 110 to low 130s range, the thought is that it's more likely a boy, and if it's in the mid 140s to 160 range, it's more likely a girl. Mid-130s to 140s is unpredictable -- and where a lot of heart rates fall." 

    A study done in 1993 at the University of Kentucky seemed to prove this theory right, finding that the fetal heartbeat could be used accurately to predict the sex of 91% of boys and 74% of girls. But subsequent studies all disagree. "I also tell my patients that there must be other atmospheric conditions that affect this because you have a run of babies where this theory tends to work, and then suddenly you can't get one right to save your life!" Crane says.

  • The "linea nigra" -- the dark line that some women get running from the pelvic bone, mid-abdomen, to the belly button or as far as the xyphoid (the bottom-most part of the rib cage in the center or tip of the sternum). "The theory goes that if the linea nigra runs to the belly button, it's a girl, and if it goes all the way up to the xyphoid, it's a boy," Crane says.

  • The Drano test. "Apparently if you take old Drano, manufactured before a particular year in the 1980s, and mix it with the pregnant woman's urine, it turns brownish if it's a girl or bluish-green for a boy," Crane says. "How this one got started, I have no idea!" Does it work? "You got me!"

  • If the woman looks prettier during her pregnancy, it's a boy. If you're having a girl, you tend to lose some of your looks, because she's taking your beauty," Voto says. What about Schaffer's gas station attendant who told her just the opposite? "That's why we call them old wives' tales!"

      In fact, many of the traditional tales about how to predict your baby's sex seem to flip-flop depending on who's doing the telling. If you're carrying low, it means a girl. No, it means a boy. If the "ring trick" results in a pendulum-like swing, it means a boy. No, a girl.

      'A Mystery and a Miracle'

      Science -- in the form of modern imaging technology -- is far more reliable at predicting baby's sex, but even ultrasound can't always boast 100% accuracy. Whether your ultrasound gets it right depends on a lot of factors, including how far along you are in pregnancy, the quality of the equipment, and most important, cooperation from the baby. Fetal positioning or movement when the ultrasound is done may mean the technician can't get a clear view of the genital area.

      Crane doesn't think these tales will ever disappear. "The sex of a child can hold particularly significant meaning to a woman.  Mostly we say we just want a healthy baby but secretly (and not so secretly), many of us have dreams of mothering a child of a certain sex," she says.

      "There is so much we do not know about pregnancy and the growing baby within us. It's a mystery and a miracle every time.  We know the science behind it, but there are such deep emotions and awe at what happens to our body and mind during pregnancy. Therefore, myths are generated to perpetuate our sense of awe around this process. And heck -- it's fun to play around with this stuff!"

      Published July 28, 2003.

      SOURCES: Birth, September 1999. Journal of the Kentucky Medical Association, September 1993. Tara Voto, RN, BSN, labor and delivery nurse, St. Barnabas Hospital, Livingston, N.J. Patricia Crane, MSN., CNM, director, nurse midwifery service, University of Michigan Health Systems.

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