What is the right weight gain in pregnancy? What are the potential risks for women to go up a little too much? And for those who increase too little? The latest indications of science
Weight in pregnancy
Those who are expecting a baby know: among the indications they receive from the gynecologist or midwife from the first visit, there is that of keep weight gain under control. Sometimes, in fact, there is a tendency to let go a little – it is difficult to eradicate from the mind the so common idea that in pregnancy it is necessary to “eat for two” – but Excessive weight gain risks hurting both mother and baby. On the contrary, those who are already very thin should be careful not to increase too little, because even in this case there are risks.
But beware: it’s not just how much weight you gain (or don’t take) in pregnancy that impacts maternal and fetal health. According to a major study published in May 2019 in the Journal of the American Medical Association (Jama), what counts a lot – indeed, even more – is the starting weight, the one you have when you have a positive pregnancy test in your hands. Also in this case, the most critical situations concern excessive starting weights (overweight and above all obesity) or too low (chronic underweight).
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How much weight you need to gain in pregnancy
The indications considered most valid by the international scientific community are those formulated by the American Institute of Medicine, in collaboration with the National Research Council. Obviously, these are indications that take into account the weight that the expectant mother had before pregnancy. “Means that there is no ideal weight gain for the nine months, valid for all “confirms the gynecologist Stefano Bianchi of the San Giuseppe Hospital in Milan. “On the contrary, the ‘right’ weight to be taken must be commensurate with the starting weight”.
The guidelines on weight in pregnancy
In reality, more than the weight as a whole, experts and guidelines refer to the so-called body mass index (if you don’t know yours, you can calculate it online here), which is a sort of relationship between the actual weight and the person’s ideal weight and is calculated by dividing the weight in kilograms by the square of the height expressed in meters. On the basis of the value obtained, the following conditions are distinguished:
- underweight: less than 18.5 kg;
- normal weight: between 18.5 and 24.9 kg;
- overweight: between 25 and 29.9 kg;
- obesity: more than 30 kg, with further subdivisions into three classes of increasing severity.
Here are the American indications, based on the pre-pregnancy body mass index.
- Increase indicated in starting conditions of underweight: 12.5-18 kg
- Increase indicated in starting conditions of normal weight: 11.5-16 kg
- Increase indicated in starting conditions of overweight: 7-11.5 kg
- Increase indicated in starting conditions of obesity: 5-9 kg
Slightly different, but largely overlapping indications are those provided by the international study group on maternal obesity and childhood outcomes in the journal Jama. We also see these: between 14 and 16 kg for women who are underweight; between 10 and 18 kg for women of normal weight; between 2 and 16 kg for those who leave in a condition of overweight and no more than 4-6 kg for those who leave in a condition of obesity.
The main difference is a slightly wider range for those who start from normal weight conditions or from a slight overweight, which are precisely the least problematic because they indicate an already good starting metabolic and nutritional situation. On the other hand, there are some more restrictions for those starting from a situation of obesity, certainly more critical.
The Risks of Excessive Weight Gain and Excessive Weight in Early Pregnancy
“There are various reasons to advise against gaining too much weight during the months of waiting, as well as to advise against starting it in conditions of overweight and obesity” he says. Angela Spadafranca, biology specialist in food science and pregnancy nutrition expert, freelance professional and research collaborator at the Mangiagalli Clinic.
“First: because all these conditions they increase the risk of various complications, such as gestational diabetes, preeclampsia, fetal macrosomia (when the full-term fetus is estimated to weigh more than 4.5 kg), difficulty in childbirth, caesarean section “.
“Second, because more and more data suggests that a nutritional status or a altered metabolic picture during pregnancy, as is the case with obesity, they can have long-term effects on the child’s health, for example by increasing the risk that he himself will develop obesity “.
“Third, because the mother who gains excess weight during gestation becomes in turn at risk for developing diabetes, metabolic syndrome and cardiovascular disease“.
The risks of a too late weight gain and a condition of excessive thinness in early pregnancy
If “too much” is risky, the same goes for “too little”. “In fact, little is said about it – underlines Bianchi – but also women who find themselves in these conditions run more risks, in particular preterm labor, with all the consequences this can have on the child’s health in the short and long term, and of poor fetal growth, resulting in a child presenting at birth small for gestational age“.
In turn, the small child for gestational age (doctors call it Sga, an acronym for the English words small for gestational age) can show in the short term an increased risk of respiratory complications or inadequate and long-term growth (even in adulthood) an increased risk of metabolic and cardiovascular diseases.