Being a doctor, I often get asked medical questions. The queries are typical and standard. Seniors wanting to know about triggers that shoot up their blood pressure, young ladies looking for an all-in-one magical serum, older ladies asking for recommendations for pigmentation changes, young mothers asking about plastic surgery procedures…you get the drift.
But the other day, I was taken aback by a rather unusual question- a young lady wanting my opinion about the veracity of diet determining the sex of your unborn child!
The only thing I could say to her was I had heard of these old wives’ tales but that I didn’t believe maternal diet had any impact.
But what does modern science say? Is it possible?
I scoured through medical literature to find out the answer. Below you will read briefly about some studies that have tried to answer this question.
ANIMAL STUDIES
Salty Foods
In this 1986 study, 86 adult female rats were fed diets containing 0.08 to 4% salt from a minimum of 1 week before breeding and throughout the pregnancy. It was seen that as the salt intake increased, the proportion of male progeny decreased. No effect on the litter size or the general health of the offsprings were noted.
The researchers postulated that the dietary salt content might affect the way genes are expressed.
The source and the number of calories
This study compared two sets of mice with different nutritionally complete diets.
Diet 1 (Low-fat) was low in saturated fat, with sugars and complex carbohydrates supplying most calories.
Diet 2 (High-fat) was very high in saturated fat, with 54% of its energy provided as lard.
The mice were maintained on their respective diets from the age of 30 days, and with time, each group had 4 litters. The high-fat diet produced significantly more males than the low fat diet.
Calcium
In another study on female mice, they were divided into 2 groups.
One group received a low calcium diet (0.10% calcium), and the other group a standard diet (0.85% calcium) which provided sufficient calcium for reproductive-age mice.
The calcium-deficient diet group produced fewer offspring and relatively fewer male pups than the group that consumed a calcium-sufficient diet.
HUMAN STUDIES
Calories and specific food items (Cereously?!)
This oft-quoted study published in 2008 has a very catchy headline-
You are what your mother eats: evidence for maternal preconception diet influencing fetal sex in humans.
The study analyzed the pre-conception food intake of 740 British women.
And what did it find?
The calorie intake of these women was divided into three tiers.
The top tier with the maximum calorie intake gave birth to more males (56%) vs. the group with the lowest least calorie intake with more female births (45%).
The women who consumed higher calories were also found to have consumed varied nutrients like potassium, calcium, and vitamins C, E, & B12.
The researchers also sifted through the 133 types of food items from the food intake data of the study population, and only one item of all these was strongly associated with the sex of the baby- the humble breakfast cereal.
The women who consumed at least one bowl daily produced more male infants.
No other food item showed a significant association with the baby’s sex.
Previous research has suggested that higher blood sugar levels (glucose) favor the growth of male embryos.
The researchers in this ‘cereous’ study hypothesized that women who missed breakfast or had lower calorie intake ended up giving the body a signal that the conditions are not optimal for a male child.
Evolution supposedly will allow for a female progeny when maternal nutrition is poor as the female child, no matter how weak, will likely mate and bear children, whereas a weak male child that comes forth from a weak mother will be at an evolutional disadvantage with poor mating prospects!
The following factors in the mother were found to be irrelevant to the sex of the fetus:
- Smoking
- Caffeine intake
- Maternal age
- Weight and Body Mass Index (BMI)
- Education level
But before your start filling yourself up with cereals or avoiding them altogether to balance your family, here is what you should know:
- This study has not been replicated yet.
- The statistics used, which determine if the study’s result is just a chance finding or is due to an actual real cause, have been called into question.
Maternal Muscle Mass
This 2003 study titled ‘Strong mothers bear more sons in rural Ethiopia’ involved 324 women in a food-stressed agro-pastoralist community in rural Southern Ethiopia.
The association between the sex of the most recent child born and the nutritional status as measured by the body mass index (BMI) and the mid-upper arm muscle circumference (MUAMC) was studied.
The researcher found that the effect of the muscle mass as measured by the arm circumference was strongly correlated to male birth – women in the top 25% of the muscle mass were twice as likely to give birth the boy vs. the ones in the lowest 25.
However, a study that sought to replicate the above study using a larger sample of Ethiopian births failed to replicate the results of the aforementioned study.
The Verdict?
The idea that maternal diet can influence the sex of the child is already a part of the traditional wisdom of many cultures.
There is, however, no consensus about the probity of these dietary manipulations. What we do know for certain is that a mother needs to eat a healthy balanced diet before, during, and after pregnancy for the optimal health of both her and the offspring.
A healthy child and mother should be the end goal of any pregnancy.
Trivia
Source: Wikipedia.
Whereas the above studies may be a fun thing to read, in many societies, gender-biased sex selection is a problem of great magnitude. According to the State of World Population 2020, around 140 million women are ‘missing’ worldwide. The biological normal sex ratio at birth naturally falls around 102-106 males per 100 females. However, ratios as high as 130 per 100 females have been observed, which points to gender-based sex selection due to the easy availability of technologies like ultrasound.
In India, the PCPNDT Act of 1994 bans prenatal sex determination. Every specialization or medical branch that has the potential of sex determination or selection (e.g., radiology centers, genetic counseling centers, genetic laboratories, or genetic clinics engaged in counseling or conducting pre-natal diagnostics techniques, like in vitro fertilization centers) comes under the preview of the PCPNDT Act that explicitly bans sex determination. Some exceptions are provided, like in cases of sex-linked disorders.
