Factors Associated with Excessive Gestational Weight Gain Among Brazilian Mothers

Introduction

The gestational period causes several physiological and metabolic changes in the woman's body associated with the growth and development of the fetus, in addition to changes that include increased blood volume and adiposity, breast growth, placental evolution, and amniotic fluid production, which all contribute to the gestational weight gain (GWG). ¹

When GWG is insufficient, it may compromise intrauterine growth favoring the occurrence of “small-for-gestational age” newborns and also premature labor. ² However, when in excess, it can lead to hypertensive syndromes, gestational diabetes mellitus, cesarean delivery, and neonatal risks, such as fetal malformation, “large-for-gestational age” newborns, and an increased risk of mortality.^2,3

Moreover, GWG also has implications for maternal health after childbirth. A large meta-analysis performed by Nehring et al. ⁴ showed that women with excessive GWG present greater gestational weight retention for up to 3 years after giving birth, and this was becoming a major risk factor for increasing overweight in this population. ⁴

The problem of inadequate GWG may occur due to several factors, including eating habits, nutritional status before pregnancy, sedentary lifestyle, prenatal care, and socioeconomic status. ¹

Excess weight before gestation, for example, is associated with a greater difficulty in maintaining GWG within the parameters considered adequate. ⁵ In addition, there is an increase in appetite and food intake during pregnancy and women are often encouraged by popular belief to eat high-energy foods rich in carbohydrates and fats that contribute to excessive GWG. ⁶

Given the information above, this study aimed to investigate the factors associated with excessive GWG among Brazilian mothers in a public maternity unit.

Materials and Methods

This is a cross-sectional study conducted with mothers in a public maternity unit in a Brazilian metropolis (Belo Horizonte, 1.43 million inhabitants, 330.9 km²) from August to December 2015. All women who attended the maternity during this period and met the inclusion criteria were invited to participate in the study. We included women between the first and 10th day after childbirth, without age restrictions. Using the Epi Info™ 7 software, we estimated the need for 50 participants, adopting a 95% confidence interval, 5% error, a formula for descriptive purposes, ⁷ and a finite population (270 women per month), using the prevalence of excessive GWG described in a similar study (30.5%). ¹

All participants were clarified about the methods and objectives of the research and then signed the informed consent term. The project was approved by the Brazilian Research Ethics Committee under the number 52537215.5.0000.5149.

Participants were interviewed by trained health professionals through a structured questionnaire developed especially for this research. The following socioeconomic, demographic, and health status information were collected: per capita income (up to ½ minimum wage or higher than ½ minimum wage), education (elementary school, high school, or higher school), professional occupation (paid work, student, housewife, or unemployed), age (adult or adolescent), marital status (married/stable union), parity (one child or more than one child), prenatal institution (public, private), number of prenatal consultation (up to six or more than six), route of delivery (cesarean or vaginal), complications during delivery (yes or no), breastfeeding (yes or no), and exclusive breastfeeding (yes or no). Women were also evaluated for eating habits and anthropometry.

To evaluate eating habits, the qualitative Food Frequency Questionnaire (FFQ) validated for the Brazilian population by Giacomello et al. ⁸ was adapted. To better meet the objectives of this research, foods were grouped into markers of a healthy diet (fruits, vegetables, whole grain cereals, and milk and dairy products) and markers of an unhealthy diet (sugar and sweets, sugary drinks, fried foods, and processed foods—canned and frozen meals). The consumption of these foods were categorized as frequent (three times or more a day), moderate (one to six times a week), and rare (never to three times a month). Similar classification has already been adopted in other studies. ⁹

Pregestational weight and GWG were obtained consulting the woman's gestational record. The body mass index (weight/height²) before pregnancy was classified according to the World Health Organization guidelines. ¹⁰

The GWG was classified according to the nutritional status before pregnancy. ² Mothers with preterm labor (≤37 weeks) had the values corrected according to the gestational week, by multiplying the recommended weight gain per week by the gestational age.

The palpation of malleolar edema technique was performed for liquid retention analysis, and classification was performed according to Duarte and Castellani. ¹¹

Data were analyzed using the Statistical Package for Social Sciences software version 19. The Kolmogorov–Smirnov test was applied to evaluate the adhesion of the variables to the normal distribution. Afterward, descriptive analysis was conducted by calculating frequencies and measures of central tendency and dispersion. The association between two qualitative variables was evaluated using the chi-square and Fisher's exact tests, with the Bonferroni correction. The significance level of 5% was adopted.

Results

A total of 98 mothers with an average of 25.4 ± 6.8 years of age and 2.5 ± 1.2 days after delivery were evaluated. The socioeconomic, demographic, and health status information of the sample are described in Table 1.

The majority of the sample reported being married (63.9%), having paid work (53.6%), and having a per capita income above half the minimum wage (57.4%). Regarding prenatal care, 89.8% used the available public health service and 63.3% attended to more than six prenatal consultations.

Vaginal delivery was performed by 72.4% of the mothers, and 19.4% reported some complication during delivery. At the time of the interview, 88.8% of the sample was exclusively breastfeeding.

Regarding the nutritional status (Table 2), 42.9% of the sample was overweight before pregnancy and 32.6% presented some degree of edema after childbirth.

According to the FFQ, there was a frequent intake of vegetables, fruits, and milk and dairy products in more than 70% of the sample. Approximately 80% consumed whole grains rarely and 62.2% and 29.6% reported frequent consumption of sugar and sweets and fried foods, respectively (Fig. 1).

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FIG. 1.

Frequency of food consumption according to GWG classification. GWG, gestational weight gain.

The mean GWG of 12.2 ± 6.5 kg was observed, with 39.8% of the sample classified as having excessive GWG (adequate and insufficient GWG: 31.6% and 28.6%, respectively). After the Bonferroni correction, the GWG was associated with per capita income and route of delivery (Table 1), and edema and nutritional status before pregnancy (Table 2).

Among mothers with excessive GWG, a higher prevalence of per capita income above half a minimum wage was observed when compared with those with insufficient (76.9% versus 46.1%; p = 0.011) or adequate (76.9% versus 41.3%; p = 0.003) GWG. The prevalence of cesarean delivery was higher among women with excessive GWG than among those with adequate GWG (38.5% versus 12.9%; p = 0.016).

Mothers with excessive GWG had a higher prevalence of excessive weight before pregnancy when compared with those with adequate GWG (61.5% versus 16.1%; p = 0.001). In addition, a higher prevalence of lower limbs edema was observed among women with excessive GWG than among those with adequate GWG (15.4% versus 6.4%; p = 0.012).

Among mothers with excessive GWG, only 7.7% reported frequent consumption of whole grains, whereas 51.3% had frequent consumption of sugary drinks (Fig. 1). However, food consumption was not associated with GWG (p > 0.05).

Multivariate analyses were tested, but no adjusted final model was obtained.

Discussion

The results showed an association between GWG and socioeconomic factors such as per capita income and route of delivery, as well as nutritional factors, such as edema and nutritional status before pregnancy.

The present study found a higher prevalence of per capita income above half a minimum wage among women with excessive GWG. However, the association between body weight and income is still controversial in the literature. In a cross-sectional study conducted by Magalhães et al. ¹² with 328 pregnant women from the public health service, the excessive GWG was associated with a lower income. ¹² However, national data from the Brazilian Family Budget Survey indicate a higher consumption of food groups based on carbohydrates and derivatives (37.9%) and very restricted consumption of fruits (1.2%) and vegetables (0.5%) in families with incomes of up to one minimum wage.^13,14

Cesarean delivery was also associated with excessive GWG, as described by Oliveira et al. ¹⁵ These findings can be attributed to the changes in hormonal mechanisms due to inadequate nutritional status that compromises the process of uterine contraction, impairing birth signaling, and thus leading to the necessity of cesarean delivery. Zhou et al., ¹⁶ in a cross-sectional study with pregnant women, also identified that excessive GWG was associated with health complications that commonly lead to the necessity of cesarean delivery. ¹⁶ Increased adiposity promotes a greater expression of proinflammatory mediators that contribute to various metabolic changes (such as increased blood pressure and insulin resistance) that may culminate in negative outcomes. ¹⁷

In the present study, women with excessive GWG also had a higher degree of edema. It is known that fluid retention in the cellular interstices in the maternal organism is aggravated according to gestational evolution and may be related to endocrine and physiological changes reflecting increased GWG. ¹⁸ In addition, there is a scarcity of information in the literature regarding the correction of gestational and postpartum weight according to the degree of edema, which may limit the reliable evaluation of nutritional status during this period.

The results of this study showed that women with excessive GWG had a higher prevalence of pregestational excessive weight and a high body-fat percentage. Samura et al. ¹⁹ also reported in their study that women who were overweight before pregnancy tend to gain excessive weight during gestation. ¹⁹ The high GWG is also associated with greater postpartum weight retention and increased adiposity, being these risk factors for obesity and cardiovascular diseases throughout the woman's life, ⁵ besides directly influencing the nutritional state of the baby in the first years of life. ²⁰ Thus, the appropriate GWG promotes better health outcomes not only for women but also for the newborn. ²¹

Although overall food consumption has not been associated with GWG, it is possible to verify the frequent consumption of high-energy foods such as sugary drinks and reduced intake of whole grains, which can compromise the diet quality and contribute to the increase of body weight. Grundt et al. ²² pointed out that the increase in daily intake of sugary drinks has a negative impact on the maternal nutritional status and that women with a high consumption of these beverages and other unhealthy foods presented with a higher energy intake, with an enhanced risk of excessive GWG. ²²

Considering the results obtained and the importance of maternal nutritional status as an indicator for the gestational evolution, ¹⁷ there is an emerging demand for the provision of better nutritional information and support during prenatal care to stimulate healthy eating habits and reduce the risk of negative outcomes for the maternal and child health. It is important to highlight that maternal health status is strongly associated with breastfeeding success, considering that excessive weight and other complications that may lead to the necessity of cesarean delivery, which can delay the production and ejection of breast milk and also make the positioning of the baby more difficult.^23,24

Despite the significant results, the present study has limitations due to its cross-sectional design (which does not allow for establishing definitive causal relationships between variables) and the use of secondary data (pregestational weight and GWG obtained by consulting woman's gestational record). Nevertheless, it is hoped to foment interventions on the monitoring of the GWG to favor the maternal nutritional status and to prevent excessive gestational weight retention.

Conclusions

Excessive GWG was associated with maternal socioeconomic and nutritional factors. These data may be used to guide interventions in clinical practice and highlight the importance of nutritional attention during prenatal care to monitor weight gain and prevent negative outcomes for the maternal and child health.