Weight gain in healthy pregnant women in relation to pre-pregnancy BMI, diet and physical activity

Highlights

• More than half of healthy pregnant women had a weight gain outside the IOM-guidelines.

• Women who declined activity had an almost twofold risk for too high weight gain.

• The diet of pregnant women was noticeably better than that of non-pregnant women.

• Dietary intake (vegetables, fruit and fish) was not associated with weight gain.

• Women who stopped smoking and ethnic minorities had more often too high weight gain.

• Weight gain needs to be discussed with all women, regardless of pre-pregnancy BMI.

Abstract

Objective

to explore gestational weight gain in healthy women in relation to pre-pregnancy Body Mass Index, diet and physical activity.

Design

a cross-sectional survey was conducted among 455 healthy pregnant women of all gestational ages receiving antenatal care from an independent midwife in the Netherlands. Weight gain was assessed using the Institute of Medicine (IOM) guidelines and classified as below, within, or above the guidelines. A multinomial regression analysis was performed with weight gain classifications as the dependent variable (within IOM-guidelines as reference). Independent variables were pre-pregnancy Body Mass Index, diet (broken down into consumption of vegetables, fruit and fish) and physical activity (motivation to engage in physical activity, pre-pregnancy physical activity and decline in physical activity during pregnancy). Covariates were age, gestational age, parity, ethnicity, family income, education, perceived sleep deprivation, satisfaction with pre-pregnancy weight, estimated prepregnancy body mass index, smoking, having a weight gain goal and having received weight gain advice from the midwife.

Findings

forty-two per cent of the women surveyed gained weight within the guidelines. Fourteen per cent of the women gained weight below the guidelines and 44 per cent gained weight above the guidelines. Weight gain within the guidelines, compared to both above and below the guidelines, was not associated with pre-pregnancy Body Mass Index nor with diet. A decline in physical activity was associated with weight gain above the guidelines (OR 0.54, 95 per cent CI 0.33–0.89). Weight gain below the guidelines was seen more often in women who perceived a greater sleep deprivation (OR 1.20, 95 per cent CI 1.02–1.41). Weight gain above the guidelines was seen less often in Caucasian women in comparison to non-Caucasian women (OR 0.22, 95 per cent CI 0.08–0.56) and with women who did not stop smoking during pregnancy (OR 0.49, 95 per cent CI 0.25–0.95).

Key conclusions and implications for practice

a decline in physical activity was the only modifiable factor in our population associated with weight gain above the gain recommended by the guidelines. Prevention of reduced physical activity during pregnancy seems a promising approach to promoting healthy weight gain. Interventions to promote healthy weight gain should focus on all women, regardless of pre-pregnancy body mass index.

Introduction

Gestational weight gain (GWG) is associated with the health of mothers and babies (Adamo et al., 2012). Too much GWG is associated with overweight and obesity in the long term in both mothers and their offspring (Viswanathan et al., 2008, Melzer and Schutz, 2010, Adamo et al., 2012, McClure et al., 2013). Too much GWG is also associated with pregnancy-related pathology, including gestational diabetes and pregnancy-induced hypertension (Adamo et al., 2012, Yu et al., 2013). Too little GWG is associated with prematurity and babies who are small for their gestational age (Yu et al., 2013, Pereboom et al., 2014). Given the need to prevent pathologies caused by unhealthy GWG, it is critical that professionals in antenatal care stimulate healthy GWG.

Recommendations for healthy GWG are described in the Institute of Medicine GWG-guidelines (IOM-guidelines) (Rasmussen and Yaktine, 2009). These American guidelines are used often in research around the globe, but have been used by only a small (albeit growing) number of national professional boards (Alavi et al., 2013). The IOM recommends a total GWG that is dependent on the Body Mass Index before pregnancy (pre-pregnancy BMI) (Table 1).

For all pre-pregnancy BMI groups (underweight, normal weight, overweight and obese), the recommendation for healthy GWG is the same for the first 13 weeks, from 0.5 to 2.0 kg. In the second and third trimesters of pregnancy the guidelines recommend a maximum and minimum rate of GWG per week, depending on the pre-pregnancy BMI (Rasmussen and Yaktine, 2009). IOM guidelines enable and encourage monitoring GWG from the beginning to the end of pregnancy. Given the earlier mentioned negative consequences of unhealthy GWG, and because women with too high GWG in the first part of their pregnancy have a higher risk of exceeding the guidelines in the end (Daemers et al., 2013, Davenport et al., 2013, Pereboom et al., 2014), monitoring GWG during pregnancy is important. Supportive health professionals should strive to help women reach a healthy GWG during pregnancy, i.e. a GWG within the IOM-recommendations.

Various studies of different populations of women from western countries report that the number of women achieving a healthy GWG varies between 21.6 and 48.7 per cent (Hunt et al., 2013, Rauh et al., 2013). We know from the literature that two behaviours are closely related to healthy GWG: healthy diet and engaging in physical activity (PA) (Rasmussen and Yaktine, 2009, Hill et al., 2013). Non-pregnant, healthy individuals are advised to eat 200 g of vegetables per day, two to three daily servings of fruit, fish twice per week (including fatty fish once a week) and to adapt their caloric intake to their individual PA (Agudo, 2005). Norms for healthy PA are 30 minutes of moderate-intensive PA at least five times per week (WHO, 2010). The norms for diet and PA for healthy non-pregnant individuals are applicable to pregnant women (except for women with a medical reason for adapting their lifestyle). A large number of non-pregnant individuals do not meet the norms for diet and PA (van Rossum et al., 2011, Hildebrandt et al., 2013). Little is known about pregnant women׳s eating and PA behaviour.

GWG is also associated with several factors other than diet and PA. Women with healthy GWG are more often Caucasian (Hunt et al., 2013, Pawlak et al., 2013), are better educated about GWG (Phelan et al., 2011a), do not smoke (Olafsdottir et al., 2006, Adegboye et al., 2010, Pereboom et al., 2014), are multiparous (Chin et al., 2010) are more likely to have a healthy GWG goal (Stotland et al., 2005, Cohen and Koski, 2013) and exhibit more positive self-esteem (Dipietro et al., 2003, Herring et al., 2008, Althuizen et al., 2009, Hill et al., 2013). Women with too much GWG, in contrast, more often report sleep deprivation (Gunderson et al., 2008, Kamysheva et al., 2008, Althuizen et al., 2009), a high pre-pregnancy BMI (Althuizen et al., 2009, Phelan et al., 2011b), too much GWG in the first part of pregnancy (Daemers et al., 2013, Davenport et al., 2013, Drehmer et al., 2013), low income (Paul et al., 2013) and a history of restrained eating and food insecurity, which means they do not always have enough money to buy proper food (Laraia et al., 2007, Laraia et al., 2013, Paul et al., 2013). Women with high GWG are more likely to receive inaccurate (too high) GWG advice from their health professional (Phelan et al., 2011a) and more often have disturbed blood parameters, such as thyroid hormones (Pop et al., 2013). The above-mentioned studies mostly included specific subgroups such as obese women or women with a higher risk for gestational diabetes. At present we know very little about how these factors influence GWG in interaction with each other and with pre-pregnancy BMI, diet and PA in healthy pregnant women. We assume that at least 52 per cent of pregnant women in the Netherlands are healthy (i.e. no higher risk for complications or a history of medical problems) as these women receive full antenatal care from a midwife in primary care which in the Dutch midwifery system means that there are no signs of pathology (Perinatal Database Netherlands (PRN), 2013).

Preventing unhealthy GWG is challenging. Behavioural interventions, including motivational interviewing, goal setting and tailored counselling, appear to be promising strategies for influencing diet and the PA of pregnant women with specific conditions such as diabetes or overweight (Quinlivan et al., 2011, Muktabhant et al., 2012, Adamo et al., 2012, Brown and Avery, 2012, Hill et al., 2013). Research and interventions aiming at healthy pregnant women are scarce, however, despite the fact that two thirds of this group have unhealthy GWG (Daemers et al., 2013). Efforts to increase our knowledge of the physiology of GWG will benefit from studies of the GWG distribution of healthy pregnant women and from analysis of the factors associated with (un)healthy GWG in healthy women. This knowledge is a prerequisite for developing an effective intervention for promoting healthy GWG in all pregnant women (Bartholomew et al., 2006). For that reason we conducted a study with the aim to gain knowledge on healthy pregnant women׳s GWG and to identify the factors associated with healthy GWG, including pre-pregnancy BMI, diet and PA.