Factors associated with gestational weight gain: a cross-sectional survey

Abnormal gestational weight gain (GWG) is currently a serious obstetric problem. The prevalence of inadequate GWG varies among populations. In the US, GWG was within the recommended range for 32% of women giving birth to full-term babies. In 48% of cases, the increase in weight was higher, and in 21% of the cases, weight gain was lower than that recommended by the US Institute of Medicine (IOM) [1, 2]. A survey conducted between 2006 and 2015 on over 18,000 women in rural Pennsylvania showed that only 25.3% of women in this population gained weight within the recommended range – 21.3% gained an amount below and 52.9% gained an amount above the range in the IOM guidelines [3]. In a group of over 14,000 Italian women, the recommended GWG was found in 40.8%, in 30.1% of the women, GWG was lower, and in 29.1%, it was higher than the guidelines [4]. In German studies, 37.0% of women had excessive and 27.4% had inadequate GWG, according to the US IOM criteria [5]. Studies conducted in Poland showed that 40 to 48% of patients attain a GWG above the IOM guidelines and 14 to 23% attain a lower GWG [6, 7].

Abnormal GWG can have significant importance for both short-term pregnancy outcomes [1, 8, 9] and for the long-term health of the offspring [10–13] and the mother [8, 14, 15]. Health risks related to inadequate weight gain during pregnancy involve, first and foremost, a greater risk of premature birth and a low birth weight baby and/or intrauterine hypotrophy and, consequently, an increased risk of mortality and morbidity [1, 9, 16]. Excessive weight gain is indicated as a risk factor for giving birth to a high birth weight baby compared with its gestational age [9, 17], giving birth to a baby with macrosomia [4, 9, 18], gestational diabetes [19, 20], pregnancy-induced hypertension [21, 22], caesarean delivery [23, 24], longer infant hospital stays [22] and the persistence of a higher postpartum weight for the mother after childbirth, which predisposes one to obesity later in life [8, 14, 15, 25, 26].

Maternal pre-pregnancy body mass index (BMI) [1, 27], diet [28–30], physical activity [27, 29], smoking status [31] and socio-demographic factors [1, 32–34] are listed as the main determinants of GWG. Women who were overweight or obese prior to pregnancy were significantly more likely to exceed weight guidelines [1, 27, 34]. Tielemans et al. [35] confirmed that specific dietary patterns (DP) may play a role in early pregnancy but are not consistently associated with GWG. In the meta-analysis carried out by Streuling et al. [28], five studies suggested significant positive associations between energy intake and GWG, whereas three found no significant associations. Women who remain physically active during their pregnancies have a lower risk for excessive weight gain [27, 29]. However, some of the studies did not confirm any significant associations between physical activity and GWG [36, 37]. Current smokers are at an increased risk for insufficient weight gain, and former smokers are at an increased risk for excess GWG, compared to women who have never smoked [31]. It is worth noting that some studies did not confirm the relationship between smoking and GWG [38]. Therefore, the relationship between lifestyle and GWG is inconclusive.

Studies of the impact of socio-economic factors on GWG show that in the US, women with lower incomes gained more than the recommended weight compared to women with higher incomes [31, 39]. Women with less than a high school education had higher odds of inadequate GWG [40]. Huynh et al. showed that having a college or higher education was associated with a decreased GWG for non-Hispanic white women, but an increased GWG for Hispanic women [41]. Abbasalizad Farhangi states that in Iran women with high educational attainment have a significantly higher GWG compared with low-educated women [32]. As we can see, the presented research results are ambiguous and indicate that the risk of incorrect GWG in different populations may be determined by various cultural and socio-economic factors. Thus, they should always be taken into account when examining weight gain in pregnant women.

Very few papers have been published on GWG within the Polish female population [6, 7, 42], and the relationship between dietary patterns and GWG has not been studied thus far. Dietary patterns are specific to particular populations, since they may vary with age, sex, ethnicity, cultural traditions, socioeconomic status, and food availability. Research confirms that there are important differences in dietary habits between and within Eastern and Western European countries [43, 44]. Thus, it is important to analyse them in different populations. Therefore, we have formulated a hypothesis that specific dietary patterns can be identified The aim of this study was to describe the dietary patterns in pregnant Polish women and determine the association between dietary factors, pre-pregnancy body mass index, smoking, socio-demographic characteristics and gestational weight gain.

to smoke during pregnancy more often had an inadequate GWG, compared with those who quit smoking. In women with excessive GWG, a lower adherence to prudent patterns was noted in comparison to other participants in the study. Other lifestyle elements and socio-demographic characteristics did not differ in each GWG category.

To the best of our knowledge, this is the first paper to identify the DP of pregnant women in Poland. In women in the highest quartile of the ‘prudent’ pattern, characterized by high intakes of whole grains, vegetables, legumes, sea fish, milk and dairy products, and avoiding snacking between meals, the risk of excessive GWG was significantly lower. Dietary patterns, as is well known, can differ between countries and populations, which accounts for the fact that the results obtained are not always comparable with the results of studies by other authors. Lai et al. found that the highest tertile of plant-based protein food intake was associated with a 60% lower likelihood of inadequate GWG and a 34% lower likelihood of excessive GWG [48]. Stuebe et al. [49] showed that a vegetarian diet in the first trimester is inversely associated with excessive GWG. Studies conducted in Norway showed that adherence to a regional diet rich in fruits and vegetables, potatoes, whole grains, fish, game, milk, and drinking water during pregnancy may facilitate the maintenance of optimal GWG in normal-weight women [50]. Tielemans et al. found that specific DP can play a significant role in early pregnancy but is not subsequently related to GWG [35]. However, these authors noted more moderate GWG in normal-weight women with higher scores on the ‘nuts, high-fibre cereals, and soy’ pattern than in women with a low score for this pattern. Wrottesley et al. noted that an increased intake of a traditional diet pattern high in whole grains, vegetables, legumes, traditional meats, and of a decreased intake of sugar and fat was related to a lower risk of excessive GWG [51]. Chuang et al. confirmed that appropriate GWG was related to intentional planning of meals and snacks [52]. Additionally, the results of intervention studies quite explicitly show that rationale eating habits among pregnant women contributes to the optimization of their GWG [29, 36, 53].

Several authors have shown that an unhealthy DP is significantly correlated with excessive GWG [49, 51, 54], although our study did not confirm such a relationship. Unambiguous scores related to the abovementioned associations may have occurred because dietary patterns vary according to age, ethnicity, culture, and other lifestyle factors. In a study conducted among Swedish women, their intakes of caloric beverages, snacks, fish, and bread were positively related to excessive GWG [30]. Uusatilo et al. found that greater adherence to a ‘fast food’ DP, characterized by high intakes of fast food items such as hamburgers and pizza, as well as sweets, soft drinks and added sugar, was positively associated with GWG [54].

The results of our study showed that the factors related to inadequate GWG were pre-pregnancy BMI, smoking and parity. Being underweight pre-pregnancy was significantly correlated with gaining too little weight compared to gaining weight within the guidelines. It is commonly emphasized that being underweight results in a higher risk of insufficient GWG, whereas being overweight and/or obese at the time of conception is related to a higher risk of excessive gain [1, 6, 27, 30]. Fontaine et al. showed that 33 to 50% of healthy weight women and 50 to 75% of overweight and obese women had excessive GWG [55]. Heerman et al. found excessive GWG in 55.0% of mothers who were overweight before pregnancy, in 43.7% of those who were obese, and only in 37.5% of mothers who were underweight before pregnancy [56]. The results of our analyses agree with those of other authors.

The factor that strongly determined GWG in our study was quitting smoking. The results of several other papers also confirmed that women who quit smoking after conception gain much more weight than women who had never smoked [57–59]. Research carried out in the general population suggests, that heavy smokers (≥25 cigarettes per day) and those who were obese before quitting gain the most weight [60]. Although quitting smoking is a significant health-promoting change in lifestyle, it can also lead to negative metabolic consequences. Bush et al., on the basis of a literature review, found that weight gain related to quitting smoking results mainly from a decline in resting-state basal metabolism [61]. Furthermore, nicotine in cigarettes is an appetite suppressant. Depriving oneself of it results in an increase in appetite and in emotional eating, calorie misperception, and a greater craving for sweets, which may lead to excessive calorie intake.

The results of our study are consistent with reports of other authors that primiparous women gain more weight and that the probability of the occurrence of excessive GWG is higher compared to their multiparous counterparts [36, 62]. Only Hill et al. did not find any differences in GWG between primiparous and multiparous women [63]. In several papers, there were no significant associations reported between age and GWG [64–66], which is in agreement with the results of our study. In other studies, it is emphasized that a lower GWG is present in older women [1, 36, 67]. However, the results obtained by these authors usually concern women aged up to > 35 and not ≥30, as is the case in our analysis.

Despite the large number of publications regarding the association between socioeconomic status and GWG, the literature is inconsistent [32, 33, 39–41, 68, 69]. Women with low income have an increased risk for both excessive and inadequate GWG [69]. The reason for this is largely due to a lack of understanding of the importance of a healthy diet during pregnancy as well as limited access to healthy food. However, Guilloty et al. found that socio-demographic characteristics were not associated with GWG, which is consistent with the results of our studies [70]. Among the participants in our study, there were few women (only 1.75%) who reported a lack of adequate money to buy necessary food. Therefore, the results obtained should be considered with great caution. In most studies, a higher risk of gaining weight outside of the recommendations was found in women with a lower level of education [32, 40, 71, 72]. Cohen et al. suggested that higher education plays a role in healthier GWG for some, but not all, groups of pregnant women [33]. In most cases, higher education was associated with a lower chance of inadequate GWG. Educational attainment was also associated with excessive GWG; however, ethnicity and pre-pregnancy overweight status both modified this association, sometimes in different directions. In addition, the correlation analysis among the participants in our study suggests that a high adherence to the unhealthy DP negatively correlated with a higher level of education (Spearman’s rank correlation coefficient = − 0.28; p < 0.05; data not shown). Thus, although there is no direct relationship between education and GWG, this factor may affect the GWG indirectly by modifying the diet. This issue requires confirmation with a larger group of women.

The main limitation of the study is the lack of data concerning the physical activity of the women subjects, which can have an influence on GWG [27, 29]. However, some of the studies did not confirm any significant associations between physical activity and GWG [36, 37]. Moreover, for the evaluation of food intake, a non-validated, authors’ original semi-quantitative questionnaire was applied. Standard questionnaires are very long and extensive, and in the opinion of the management of the hospital, they could be an excessive burden for women shortly after delivery. They could also contribute to lower response rates among women. The results obtained should also be treated with caution because of the small number of obese participants (N = 6; 1.31%), as well as the small number of those who were overweight (N = 38; 8.30%). However, it is known that in the Polish population, excessive body mass occurs least often among young women. In a representative group (i.e., 1129 female university students aged 20–24 years from the south of Poland), it was noted that 6.5% were overweight and only 0.5% were obese (BMI was calculated on the basis of the measurements of body height and mass) [73]. There was also a small number of women who quit smoking during pregnancy (N = 17; 3.7%). Therefore, the smoking results should also be approached with great caution.

Three dietary patterns, characteristic of pregnant women in Poland, were identified: ‘unhealthy’, ‘varied’ and ‘prudent’. The risk of excessive GWG was lower in women with a high adherence to the prudent DP, which was characterized by a high intake of vegetables, legumes, whole grains, sea fish, milk, and dairy products, as well as a larger amount of total drinks, the consumption of a larger number of planned meals, and avoiding snacking between meals. The factors that was positively associated with a higher risk of excessive GWG in the study population were quitting smoking at the beginning of pregnancy and excessive body mass at the time of conception. The risk of inappropriate GWG (both too low and excessive) was smaller in the third and subsequent pregnancies compared to the first. Being underweight pre-pregnancy increased the risk of inadequate GWG and decreased the risk of excessive weight gain. Women who were overweight or obese pre-pregnancy and those who quit smoking at the beginning of pregnancy should be provided dietary guidance to prevent them from excessive GWG. Prevention programmes for pregnant women, developed to optimize their GWG, should include socio-economic factors, cultural traditions, and dietary patterns that are specific to a given population.