fat mum, fat baby?

In my neverending quest to bring you the latest in pregnancy news (and always with a critical eye), I thought you might be interested in hearing about the latest study from the April issue of the American Journal of Obstetrics and Gynecology suggesting that pregnant women who gain the recommended amount of weight set by the Institute of Medicine (IOM) are at risk of having 'fat' babies. Now, not only are women apparently 'at risk' for having overweight babies if they exceed the guidelines based on their body mass index (BMI), women are actually being encouraged to gain the least amount of weight possible during pregnancy. I thought I would take this opportunity to talk about how weight gain guidelines in pregnancy have changed over the years and how this new study can be potentially damaging to the self-esteem and body image concerns of new mothers.

Maternal obesity has been major concern of doctors not only because of the risk of ‘postpartum obesity’ but also for a long list of undesirable medical risks to the unborn child and as a predictor of impending toxaemia.[1] In the 19th century, maternal weight gain was of considerable concern primarily for fear of difficult delivery of large babies, particularly during a time when maternal mortality was high and cesarean deliveries were a last and not entirely safe alternative. Accordingly, the first study exploring maternal weight gain was published in 1901 showing that reduced intake during pregnancy resulted in lower birth weights.[2] Successive studies following the publication of this first report placed increasing emphasis on weight gain and doctors began to closely document weight to reduce risk to the fetus.[3] By the 1930s, pregnant women were urged to reduce their intake of salt and to gain no more than 6.8kg and consequently, low maternal weight gains were recorded up until World War II.[4]

In the 1950s and 1960s, several studies of gestational weight and pregnancy nutrition were conducted and concluded that high pregnancy weight invariably led to high birth weights.[5] The authoritative American medical textbook, Williams Obstetrics advised in 1966,

Excessive weight gain in pregnancy is highly undesirable for several reasons; it is essential to curtain the increment in gain to 25lb (12.5kg) at most or preferably 15lb (6.8kg). The experienced obstetrician is convinced of the complications, both major and minor, caused by excessive weight gain in pregnancy. Although restriction of the gain in weight to 20lb (9.1kg) may be difficult in man cases, requiring careful dietary control and discipline, it
is a highly desirable objective.[6]

Many medical textbooks established the same guidelines at the time; earlier editions recommending more stringent regulations of weight gain. It was not until the 1970s that the recommended range of pregnancy weight gain was raised to account for pre-pregnancy weight; women who were considered to be underweight pre-pregnancy were allowed to gain more than women of ‘normal weight’, between 12 and 14kg. Following the new recommendations, infant birth weight and pregnancy weight gain both steadily rose.[7] By 1976, women were encouraged to be liberal with their intake during pregnancy to a total of 2,400 kcalper day. Whilst the recommended amount of kilojoules during pregnancy was steadily on the rise by 1974, ironically it was during the 1950s that the daily allowance of kilojoules was the highest at 2700kcal per day at a time when women were encouraged to restrict their weight gain the most.[8]

Recommended maternal weight gain nearly doubled from the 1930s to the 1980s and the strict surveillance of weight gain also became slightly less stringent. Weight ranges were reassessed again in 1990 to confirm not only the target ranges for maternal weight gain but also to base those amounts on each women’s body mass index (BMI = kg/m2), a measure of body ‘fat’ based on height and weight. Scientists have had to account for the fact that in the past twenty years, 'Western' women (Australia, America, UK) have become much taller and heavier, affecting pregnancy outcomes.

In accounting for ‘body mass’ or pre-pregnancy body ‘fat’, the new guidelines allow for women with a ‘normal’ body mass to gain between 11.5 and 16kg. According to the 1990 Institute of Medicine (IOM) regulations, women with a lower BMI are permitted to gain up to 18kg and women with a higher BMI can gain 11.5kg at the most. However, the issue of maternal weight gain is still quite controversial. In a review of studies of pregnancy weight gain over the last 50 years, Abrams et al conclude that there is ‘no evidence supporting the concept that routine weighing of pregnant women should be discontinued or that restricting weight gain in normal pregnancy is either safe or beneficial’.[9] Abrams et al also suggest that even though recommended weight gain ranges have become more liberal as has clinical surveillance of maternal weight gain, women are still not gaining weight within the IOM ranges most likely as a result of weight and body image issues.[10]

With this in mind, it is fairly horrifying to me to think that given that the IOM ranges are already quite narrow and more than 10 years old, rather than making the guidelines more liberal to account for body image issues in pregnancy, women are being encouraged to consume less and monitor their weight more closely during pregnancy. It's not hard to see why the cult of the skinny pregnancy is overwhelming first time mothers and potentially putting young women off motherhood who are scared to death that their bodies will be 'damaged' forever.

More information on the new study is available here:
http://www.medicalnewstoday.com/medicalnews.php?newsid=66995
http://www.foxnews.com/story/0,2933,263225,00.html

[1] John W.C. Johnson and Michael K. Yancey, ‘A critique of the new recommendations for weight gain in pregnancy’, American Journal of Obstetrics and Gynecology, vol.174, no.1, 1996, 254-8.
[2] L.Prochownick, ‘Ueber Ernahrungscuren in der Schwangerschaft’, Ther. Monatsch, vol.15, 1901, 446-63.
[3] See also C.H. Davis, ‘Weight in pregnancy; its value as a routine test’, American Journal of Obstetrics and Gynecology, vol.6, 1923, 575-81.
[4] National Academy, Historical Trends, 38; A.W. Bingham, ‘The prevention of obstetric complications by diet and exercise’, American Journal of Obstetrics and Gynecology, vol.23, 1932, 38-44.
[5] N.J. Eastman and E.Jackson, ‘Weight relationships in pregnancy: The bearing of maternal weight gain and pre-pregnancy weight on birth weight in full-term pregnancies’, Obstet. Gynecol. Surv. Vol.23, 1968, 1003-25; R.C. Humphreys, ‘An analysis of the maternal and foetal weight factors in normal pregnancy’, Journal of Obstetrics and Gyecology, British Commonwealth, vol.61, 1954, 765-71.
[6] N. Eastman and L. Hellman, Williams Obstetrics, 13th ed., New York, Appleton-Century-Crofts, 1966, 326.
[7] Barbara Abrams, Sarah L. Altman and Kate E. Pickett, ‘Pregnant weight gain: still controversial’, The American Journal of Clinical Nutrition, vol.71, 2000, 1233S-41S.
[8] National Academy, Historical Trends, 40.
[9] Abrams et al, ‘Pregnancy weight gain’, 1240S
[10] Ibid