Days until birth: 126聽聽聽聽聽聽聽聽聽聽聽聽聽
Waist size: 85 centimetres (33.5 inches)
Deciding whether or not to find out the sex of our unborn child was a dilemma that plagued us for weeks. Would it spoil the surprise? Even without getting a definitive ultrasound examination to tell us the sex, there are any number of folklore prediction methods 鈥� but is there any science behind them?
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Old wives鈥� tale 1: Bad morning sickness means you鈥檙e having a boy
I didn鈥檛 suffer morning sickness, so according to this rule, I should be expecting a girl.
The opposite is true, in fact: mothers with severe pregnancy sickness are more likely to have a girl. In 1999, researchers analysed records of 8186 women admitted to hospital in Sweden with pregnancy sickness and found that 44.3聽per cent of them gave birth to boys, versus 51.4聽per cent of the general population (). They blame higher levels of the pregnancy hormone human chorionic gonadotropin (hCG) in women carrying girls.
Curiously, Henrik Toft S酶rensen of Aarhus and Aalborg University Hospitals in Denmark wrote to The Lancet the following month claiming that the sex ratio also seemed to be influenced by marital status, with fewer boys born to single mothers.
In a separate study, he also found that women with severe pregnancy sickness were more likely to give birth to girls; the correlation was even stronger in single mothers. Among women with severe sickness, 46.5聽per cent gave birth to boys, compared with 51聽per cent of other women. Within the pregnancy sickness group, 40聽per cent of women who lived alone had boys, against 45聽per cent of women who lived with their partner ().
Old wives鈥� tale 2: Fetal heart rate predicts the baby鈥檚 sex
According to this rule 鈥� it鈥檚 been around for 30 years, so I class it as an old wives鈥� tale 鈥� if your fetus鈥檚 heart rate is above 140 beats per minute (bpm) you鈥檙e expecting a girl, and if it鈥檚 below you鈥檙e expecting a boy. I鈥檝e had the pleasure of listening to my baby鈥檚 heart rate twice in the past fortnight, and the last time it was 130聽bpm 鈥� so I should be expecting a boy.
However, fetal heart rate tends to decrease as pregnancy progresses, from 170 to 200聽bpm at 8聽to 10 weeks down to 120聽to 160聽bpm by mid-pregnancy. And according to published studies there seems to be little difference between boys and girls, at least during early pregnancy.
In one study, researchers used ultrasound to measure fetal heart rate in 477 fetuses before 14 weeks of pregnancy. The average heart rate of girls was 151.7聽bpm, while for boys it was 154.9聽bpm 鈥� not a large enough difference to be statistically significant ().
The only time when , when female babies seem to have faster heart rates than males; the reason is unknown.
Old wives鈥� tale 3: Weird food cravings = a boy
One friend told me that my aversion to lettuce means I鈥檓 going to have a boy. I couldn鈥檛 find any science to support this, but there is some evidence from a Boston hospital study that found expectant mothers have bigger appetites on average if they are carrying a boy rather than a girl.
I鈥檓 definitely hungry all the time, but that might just be because of pregnancy in general. The problem is: how do you know what constitutes a big increase in appetite? Indeed, the authors of the Boston study admit that the difference in appetite is not striking enough to predict the sex of a baby with accuracy.
Old wives鈥� tale 4: Women 鈥渏ust know鈥�
That mysterious thing called 鈥渇emale intuition鈥� claims power over many things, including being able to predict the sex of unborn children. Personally, I suspect it鈥檚 a cunning tactic for dismissing ridiculous baby names suggested by the male partner. Having said that, I have been convinced I鈥檓 having a girl for some weeks.
In 1998, researchers at the University of Tucson in Arizona asked 108 pregnant women to . Seventy-five of these women claimed to have an intuition about it 鈥� as either a gut feeling or a dream 鈥� and of these women, 60聽per cent guessed correctly. When women who had a preference for one sex over the other were removed from this sample, however, the 48 women that remained guessed correctly 71聽per cent of the time. Unfortunately, the study was never published, making it hard to scrutinise the details.
As well as all the tales above, of particular interest to Bumpology is the folklore surrounding the shape of the bump and its relation to the baby鈥檚 sex (). But predictions from the bump are no clearer than the other tales, and we decided to plump for a method of sex prediction that鈥檚 95聽per cent certain. We asked the sonographer to tell us if our baby was going to be a boy or a girl during our 21-week scan last week.
All the old wives鈥� tales got it wrong, bar one: female intuition. I鈥檓 happy to say that we鈥檙e expecting a little girl.
Read previous Bumpology columns: Active fetus, boisterous child? Uh-oh, Why do I loathe lettuce?, How does stress affect my fetus?
