Weight in pregnancy

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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 gain) in pregnancy that affects maternal and fetal health. According to a major study published in May 2022 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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In this article

  • How much weight you need to gain in pregnancy 
  • The Risks of Excessive Weight Gain and Excessive Weight in Early Pregnancy
  • risks of excess weight gain and excessive thinness in early pregnancy
  • How much should you take, quarter by quarter
  • What are the causes of excessive weight gain in pregnancy
Read also: Pregnancy, how much weight can you gain in 9 months?

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 the 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 our city. "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 kind 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 normopeso: 11,5-16kg
  • 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. Let's 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 starting 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.

Read also: I'm pregnant, do I have to eat for two?

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 , biology specialist in food science and expert in pregnancy nutrition, freelance and research collaborator at the 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 may 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".

Read also: Nutrition during pregnancy: all the answers to your (many) questions

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 of preterm birth, 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.

Read also: Fetal growth retardation: what it is, how to intervene, what are the prospects for the future

“Clearly - warns the gynecologist - we are talking about chronic underweight, of women who eat very little and badly and not of those who, perhaps due to nausea, in the first months do not put on even a pound or even lose some weight ".


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How much should you take, quarter by quarter

Institute of Medicine and National Research Council also offer an indication of how much weight (approximately) it would be appropriate to take week after week specifically. in the second and third quarter, again according to the starting conditions:

  • underweight: 440-580 grams;
  • normal weight: 350-500 grams;
  • overweight: 230-330 grams;
  • obesity: 170-270 grams.
Read also: Diet during pregnancy

What are the causes of excessive weight gain in pregnancy

Finally, the document of the Institute of Medicine and National Research Council also takes stock of the many and different factors that can influence weight gain in pregnancy. These are factors:

  • metabolic individual;
  • psychological and behavioral (for example, the habit or not to perform physical activity, which is important for containing weight gain in pregnancy);
  • cultural (such as the belief that it is necessary to "eat for two" or, on the contrary, that especially in the last trimester it is necessary to eat very little so that the child remains small, in the belief that this can simplify the birth. But be careful: as we have seen, even a small child for his gestational age runs risks!);
  • family (presence of support or not to follow a healthy lifestyle during pregnancy);
  • socio-sanitary (presence of health policies that promote awareness of the importance of pre-pregnancy and pregnancy weight; accessibility or not to gyms, etc.)

Questions and answers

What is the ideal weight gain during pregnancy?  

Weight gain during pregnancy is very different from one woman to another, and even from one pregnancy to another for the same woman. On average, the weight gain ranges from 9 to 13 kg.

I have gained more kilos than expected: do I have to worry?  

Most women lose the pounds they gained during pregnancy. Statistics from gynecologists indicate that, on average, a woman maintains no more than 1.5 kg of the initial weight. Only 15% accumulate an overweight of more than 5 kg one year after giving birth.

Read also: The first thousand days of the child. How much can you influence his future health according to epigenetics

  • pregnancy weight
  • right pregnancy weight
  • body mass index
  • pregnancy feeding
  • sports in pregnancy
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