Comprehensive Questionnaire in Postpartum Women to Assess Women’s Knowledge of the Current Weight Gain Guidelines during Pregnancy in Lower Saxony

Obesity is a major risk factor for increased morbidity and mortality. In Germany, 26.2% of all women aged 18–29 years and 41.5% of all women in the age of 30–44 years have overweight or obesity [1]. In 2017, 15.7% of pregnant women in Germany were affected by obesity at the onset of their pregnancy [2]. The prevalence of overweight and obesity in childbearing women is increasing, as is the prevalence of obesity in the general population [3]. Additionally, in Western countries, there is a trend toward an increase in the rate of excessive gestational weight gain (GWG) [4].

The high prevalence of overweight and obesity in women of childbearing age poses a major challenge to obstetricians, as it leads to an adverse maternal and fetal outcome [2, 5, 6]. Maternal body mass index (BMI) and weight gain during pregnancy are important factors for neonatal and maternal health both immediately postpartum as well into the future. Excessive GWG is associated with several pregnancy and fetal complications such as gestational diabetes mellitus, caesarean section, preterm delivery, and high birth weight [7]. Moreover, excessive GWG may influence maternal and infant long-term health. Research suggests that GWG is not only a determinant of maternal postpartum weight retention but also increases the risk of obesity in both mother and child [8].

In 2009, the American Institute of Medicine (IOM) established revised guidelines for weight gain during pregnancy. The guidelines recommend different levels of weight gain depending on the woman’s pre-pregnancy BMI [9]. According to the IOM, women with a pre-pregnancy weight categorized as underweight (BMI <18.5 kg/m²) are recommended to gain between 12.5 and 18.0 kg; women who are categorized as normal weight (BMI 18.5–24.9 kg/m²) are recommended to gain between 11.5 and 16.0 kg; those categorized as overweight (BMI 25.0–29.9 kg/m²) are recommended to gain between 7.0 and 11.5 kg; and lastly, women who are categorized as affected by obesity (all classes, BMI >30.0 kg/m²) are recommended to gain between 5.0 and 9.0 kg. These recommendations should result in averting adverse health consequences, associated with excessive weight gain during pregnancy, for both mother and child [9, 10]. The recommendation of GWG of the IOM guidelines was transferred into the guideline of the German Society of Gynecology and Obstetrics [11, 12]. However, international studies show that the rate of adherence to these guidelines has not been satisfactory, and the overall responsiveness to the guidelines is less than 30% [13].

In the last decade, various lifestyle interventions focusing on dietary and physical activity behavior have been initiated to prevent excessive GWG and minimize resulting health complications for mothers and their infants [14, 15]. Most randomized-controlled trials showed rather modest effects in the prevention of excessive GWG [16, 17]. A recent meta-analysis suggested a decrease of GWG by −0.70 kg in women receiving lifestyle advice in comparison to the untreated control group [18]. In Germany, the cluster-randomized multicenter GeliS study offering a lifestyle intervention to 2,286 women did not result in a significant reduction of women showing excessive GWG, with 45.1% and 45.7% of women in the intervention and control groups, respectively, gaining weight above the IOM recommendations [19].

There is evidence that the IOM criteria are mentioned and discussed too infrequently and inaccurately in clinical practice in general but also in Germany [20]. Nevertheless, raising awareness regarding the criteria has been shown to influence weight gain in a recommended way, improvements in diet quality, and increased physical activity in pregnant women [21].

The objective of this study was to assess women’s knowledge and examine adherence to the Institute of Medicine (IOM) criteria for weight gain during pregnancy by evaluating the information received from obstetricians and women’s knowledge about GWG. This is the first study to establish a correlation between achieving IOM criteria and being informed about the criteria, receiving recommendations, and one’s own assessment of the importance of adequate weight gain in pregnancy.

This is an analytical semi-longitudinal observational study. Any pregnant woman who gave live birth to a healthy singleton at term was included. Exclusion criteria were prematurity, fetal malformations, and multiple pregnancies as well as German language barriers, which did not allow participation in the questionnaire part of the study or if the questionnaire was not completed despite a reminder or if the participants could not be found to get interviewed.

Between August 2020 and June 2021, clinical parameters (descriptive data as maternal age, weight and height, number of births, gestational age at birth, number of examinations and ultrasounds, mode of delivery, clinical procedures, maternal and fetal outcomes, information from hospital stay) were collected by interview and collection of clinical documentation by the study team from a convenience sample of 389 singleton pregnancies resulting in live birth at the Hanover Medical School.

Weight data were retrospectively taken from the maternity record (“Mutterpass”) and peripartum medical documentation. The maternal record is a documentation booklet that is issued by the German Joint Federal Committee as part of its Maternity Guidelines and provided to women at their first obstetric check-up for a pregnancy. An English version is available at https://www.g-ba.de/downloads/17-98-4071/2021-08-19_G-BA_Mutterpass-englisch_web_WZ.pdf. Obstetricians record pre-pregnancy BMI and chart weight gain throughout pregnancy.

The definition of special outcome parameters are as follows: A pregnant woman is defined as special mental stressed if she is burdened by special family- or work-related circumstances that are apparent to the investigator. Integration problems or economic burdens count as special social stress. Both outcome parameters are diagnosed by the attending obstetrician and documented in maternal record. “Obesity diagnosed by obstetrician” means that the attending obstetrician diagnosed the pregnant woman as affected by obesity and marked this as a pregnancy risk in the maternal record. Making the diagnosis is equivalent to educating the patient as affected by obesity.

The whole collective (n = 389) was asked to participate in the survey. About half of these women (n = 202) participated in a questionnaire study and completed questions that were taken from the Electronic Maternal Health Survey (EMat Health Survey, Ockenden et al. 2016). The questions addressed information received from the obstetrician, knowledge, and concerns about GWG and change in eating habits during pregnancy. Of those participated in the questionnaire, 65.1% were married and 30.9% were single and 60.7% reported having finished high school. All data were collected within 2 days after delivery during hospital stay.

The whole sample (n = 389) was graduated into 4 BMI categories according to the World Health Organization (WHO) classification (27). In addition, the sample (n = 389) was divided into 3 GWG groups, women who gained insufficient, recommended, and excessive weight during pregnancy [9]. Main investigated outcomes were the classification of sample into 3 GWG and BMI groups and their comparison to women’s knowledge and adherence to IOM criteria for weight gain during pregnancy. Receiving recommendations and one’s own assessment of the importance of adequate weight gain in pregnancy should also be examined.

This study was approved by the Local Ethics Committee of the Hannover Medical School and conducted according to the principles of the Declaration of Helsinki (approval number: 9143_BO_K2020). Informed consent was waived by the Ethics Committee due to the use of retrospective and de-identified data. However, patients who completed the postpartum questionnaire part were required to give written informed consent.

The EMat Health Survey is an electronic questionnaire that addresses women’s knowledge and perceptions of the current GWG guidelines, as well as pregnancy-related health behaviors [22]. It consists of 60 items in total and was developed to examine influential factors of weight gain among pregnant women. We translated the original English-language version of the EMat Health Survey into German using a forward-backward translation principle. Ten questions from the rather lengthy questionnaire were selected and used for this study so that the questionnaire could be completed in a face-to-face interview within 5–15 min. Women answered the questions postpartum based on retrospective behaviors and perceptions during their recent pregnancy.

• 1.

  Was this a planned pregnancy?

• 2.

  Thinking of your pre-pregnancy weight, what weight did you consider yourself? (underweight, normal-weight, overweight, obese)

• 3.

  Did your obstetrician/gynecologist talk to you about your weight and/or your weight gain limits? (yes, no)

• 4.

  Since you were not advised about target amount of weight gain during pregnancy, did you have a personal target? (yes, no) (can only be answered if questions 3 was answered as no)

• 5.

  What was the amount of weight gain advised by your healthcare provider (kg)? If no advice was given, what was your personal weight gain target for pregnancy?

• 6.

  Did your eating habits change at all during your pregnancy? (less healthy, the same, more healthy)

• 7.

  Have you eaten more food/calories?

• 8.

  Did you worry that you have gained too much weight? (never, occasionally, sometimes, frequently, always)

• 9.

  Based on your pre-pregnancy height and weight, your pregnancy weight gain should be 5–9 kg, 7–11.5 kg, 11.5–16 kg, 13–18 kg?

Statistical analyses were performed using IBM SPSS Statistics 28.0.0.0. Means and standard deviation (SD) as well as numbers and percentages were calculated to present descriptive information. Comparisons between groups (BMI pre-pregnancy, GWG) were performed using one-factor analyses of variance for continuous variables and χ² tests for categorical variables. Missing values were not replaced. The significance level was set at p < 0.05. In order to obtain a significant evaluation of the selected questions from the EMat Health Survey, a target size of 200 participants was aimed for, since test-retest reliability was assessed among a sample of 71 of the target population in the preliminary validation study [22].

Any pregnant woman who gave live birth to a healthy singleton at term was included first. After collecting the clinical parameters, all participants were asked to participate in answering the questionnaire (n = 389). Of the original 389 participants, 202 took part in the questionnaire.

The mean age at time of delivery of the 389 women was 32 years (SD 5.2), the number of living children was 1.8 (SD 1.1), and maternal gestational age at birth was 38.8 weeks (SD 2.0). The mean pre-pregnancy BMI was 25.7 kg/m² (SD 5.6), and the GWG amounted to 14.2 kg (SD 6.1) (Table 1).

Women who participated in the interview part of the study (n = 202) had fewer children and a lower BMI pre-pregnancy and at the end of the pregnancy in comparison to women who did not participate (Table 1). Additionally, less social stress was reported in the maternity records in women who agreed to participate in the interview in comparison to women who do not (social stress in %: Participants answered questionnaire: 7; participants without answered questionnaire: 17; p = 0.022).

The majority of women (65%) reported that they had not been informed by their obstetrician about the IOM recommendations regarding weight gain during pregnancy (Table 2). Of those who did not receive information about GWG, 52 (40%) reported that they used other sources of information about GWG, and 53 (39.8%) set themselves a GWG goal. The pregnant women who received recommendations about weight gain reported to have received the following recommendations: underweight women 13.4 kg (SD 2.8), normal-weight women 14.4 kg (SD 3.8), women affected by overweight 12.9 kg (SD 2.9), and women with obesity 10.8 kg (SD 3.2). The proportion of women who reported having received information about the recommended GWG did not differ significantly between pre-pregnancy weight categories or GWG categories.

When asked about the correct IOM GWG category based on their own pre-pregnancy weight, 30% of underweight, 57.3% of normal-weight, 37.2% of women having overweight, and 44.7% of women having obesity chose the correct IOM GWG category. Overall, 41 (20.5%) women reported to having eaten unhealthier food during their pregnancy, 66 (33%) reported healthier eating and 84 (42.0%) reported no change. 104 (52.5%) reported that they consumed more calories during pregnancy. Type and amount of reported food intake did not differ significantly between pre-pregnancy weight categories or GWG categories.

The majority of women were never or rarely concerned about weight gain during their pregnancy (157 [78.1%]). The higher the pre-pregnancy weight and the higher the GWG, the higher the proportion of women who were concerned about weight gain during pregnancy (χ² = 26.168, df = 12, p = 0.010 and χ² = 21.398, df = 82, p = 0.006, respectively). However, in all weight and GWG categories, the majority of women were still never or rarely concerned about their weight gain during pregnancy.

According to the maternal records, the number of routine prenatal visits in gynecological practices (11, SD 2.6) as well as ultrasound examinations (4, SD 1.6) did not differ between weight and GWG category groups. Additionally, marital status and educational level as well as the frequency of special mental or social stress during pregnancy did not differ between groups.

Pre-pregnancy BMI was 25.7 (SD 5.6) kg/m², with 97 (24.9%) of the participants being affected by overweight and 81 (20.8%) obesity. Obstetricians diagnosed obesity in only 45 (11.7%) of all women, and specifically in 37 (46.3%) of women who presented with obesity (Table 3).

In the subgroup of women who also participated in the questionnaire study, with the exception of underweight women, the agreement between their actual pre-pregnancy weight category and their self-identified weight category was decreasing with increasing weight; 50% of underweight women, 90.9% of normal-weight women, 30.2% of women with overweight, and 1.5% of women with obesity identified their pre-pregnancy weight category correctly.

Participants gained on average 14.2 (SD 6.1) kg during pregnancy, with 76 (19.5%) gaining weight below, 117 (30.1%) within, and 196 (50.4%) above the recommended IOM guidelines. Kilograms GWG differed significantly between pre-pregnancy weight categories, with underweight patients gaining the most (15.6 [SD 4.9] kg) and women with obesity gaining the least weight (12.3 [SD 7.8] kg) (F = 3.484, p = 0.016). 54 (66.7%) of women with pre-pregnancy obesity and 65 (67%) of women with overweight gained more than recommended by the IOM guidelines as opposed to 4 (30.8%) of underweight and 73 (36.9%) of normal-weight women. Excess kilograms GWG differed significantly between pre-pregnancy weight categories with women with obesity showing the highest excess GWG above IOM recommendations (7.2 [SD 6.1] kg) (F = 4.908, p = 0.003) (Table 3).

Overall, 21% of the women in our sample met criteria for obesity at pregnancy onset, and 50% gained more weight during pregnancy than recommended by IOM guidelines. Especially women affected by overweight and obesity seemed to underestimate their pre-pregnancy weight and were at greater risk for gaining too much weight during pregnancy. Obstetricians diagnosed obesity in gynecological practices in only 11.7% of all women, specifically in 46.3% of women who presented with obesity and thus made aware of pathological weight in pregnancy. The majority of women reported that they had not been informed by their obstetrician about the IOM recommendations regarding weight gain during pregnancy. The number of routine prenatal visits in gynecological practices as well as ultrasound examinations did not differ between BMI and GWG category groups. Additionally, marital status and educational level as well as the frequency of special mental or social stress during pregnancy did not differ between groups. Of those who did not receive information about GWG, 52 (40%) reported that they used other sources of information about GWG, and 53 (39.8%) set themselves a GWG goal. Even though the absolute amount of weight gain was lower in women with obesity, the proportion of women exceeding IOM recommendations was highest, most likely due to the strict recommendation of 5–9 kg GWG for women with obesity. Nevertheless, only a minority was concerned about their weight gain.

While it is known that the prevalence of GWG is high, the novel aspect of the provided data is the actual knowledge of women about current GWG guidelines and how often healthcare providers inform women about these guidelines and make recommendations. Only slightly more than one third of the women in our sample reported that they were informed about GWG recommendations by their obstetrician. Additionally, obstetricians did not diagnose obesity in 53.7% of their patients even though the measured pre-pregnancy weight noted on the maternity records clearly indicated a BMI of 30 kg/m² or above. Two published studies found that about two-thirds of all participants of these studies remembered receiving GWG advice [23, 24]. A recent survey in over 1,000 women [25] found that in the USA, a majority of women (71.6%) reported that a provider discussed their expected GWG with them. Thus, the proportion of women not recalling to receive no advice regarding GWG was surprisingly high in our sample. There is evidence that lack of advice or incorrect advice might be associated with inappropriate GWG [26, 27]. However, in our sample, those who remembered that they received GWG information were not more likely to stay within GWG recommendations and were not more likely to retrospectively choose the correct GWG category based on their pre-pregnancy weight group. The one-time classification into a BMI class and education of the patient about GWG in pregnancy does not seem to be sufficient to achieve the desired GWG. Rather, to increase the pregnant woman’s awareness of correct GWG, regular follow-up and review of weight gain, with reeducation if required, seem necessary.

Of those who did not recall getting advice from their obstetrician, 40% reported that they used other sources of information about GWG. Even though we did not assess the information sources, there is evidence in the literature that women frequently receive information from nonclinical sources such as the internet or books [28]. Overall, less than 50% of women reported GWG knowledge consistent with guidelines, and this was independent of their actual GWG. Specifically, women with overweight and obesity were at greater risk of gaining excess GWG, which is in line with the literature [29, 30]. Thus, knowledge about GWG alone is not sufficient for adherence to recommendations.

Women with overweight and obesity were not less adherent to the recommended prenatal visits to their gynecologist and ultrasound examinations (according to their maternity records). They were not more stressed by mental or social issues. Excess weight gain is influenced by various modifiable and non-modifiable factors. Two typically modifiable factors are poor food choices and an increase in caloric intake (“eat for two”) [31, 32]. However, in our sample, the self-reported change in eating habits did not differ between pre-pregnancy weight groups and GWG categories.

These results show the lack of discussion of GWG in clinical routine in obstetricians’ practice and the lack of knowledge and concern of pregnant women about GWG recommendations. Considering the fact that a too high GWG can contribute to short- and long-term health complications, especially when a woman enters pregnancy already with overweight or obesity, identifying ways of achieving a healthier GWG is warranted [13]. Health practitioners should encourage a healthy nutrition and adequate weight gain during pregnancy in order to ensure favorable pregnancy and fetal outcomes and to prevent diseases later in life for both mother and child. Health professionals might be unsure what advice to give [33]. However, even if the healthcare delivery system offers support, inducing behavioral changes that influence GWG is not an easy task for pregnant women even when they are fully aware of the IOM recommendations [34]. In the last decade, various lifestyle interventions focusing on dietary and physical activity behavior have shown rather modest effects in the prevention of excessive GWG. A recent meta-analysis suggested a decrease of GWG by only −0.70 kg in women receiving lifestyle advice [18]. Influencing GWG is a complex task that must be addressed not only through professional counseling and education but also by linking it to behavioral and lifestyle interventions. A holistic approach is offered, for example, by the practical recommendations of the Germany-wide healthy start – young family network [35].

In a large German lifestyle intervention study including 2,286 women [19], 45.1% of women in the intervention group and 45.7% of women in the control group gained weight above IOM recommendations. The respective percentages for women with pre-pregnancy overweight were 65.2% in the intervention group and 69.0% in the control group and with pre-pregnancy obesity, 63.9% in the intervention group and 58.3% in the control group. The proportions are very similar to the results of our study suggesting that providing a limited amount of lifestyle advice addressing diet, physical activity, and weight monitoring within routine care during pregnancy is not effective in avoiding excessive GWG. A meta-analysis based on more than 1.3 million women in 23 studies found that only 30% of women had a GWG within the ranges of IOM recommendations and that 47% had a GWG above guidelines [13]. Interestingly, the proportion of women who gained less weight than recommended is consistent across studies with 20% [13, 36].

Our study has some limitations. We examined a convenience sample; however, this was mainly due to time constraints of the doctoral students collecting the data and not based on a systematic bias. Women who participated in the interview part, however, differed slightly from those who did not participate (number of children, pre-pregnancy BMI, end of pregnancy BMI, and special social stress as shown in Table 1). There is some evidence that women with low social status and ethnic minorities have a higher pre-pregnancy BMI [37, 38]. This could be the reason of the higher pre-pregnancy BMI in the group of nonparticipants of the questionnaire in our study. Although this sample may not be representative of pregnant women in Germany in general, the results on GWG are similar to the results reported in the literature.

We did not assess knowledge and opinions of the obstetricians about IOM GWG guidance. A recent survey indicates that most providers (87.5%) reported that they were aware of IOM guidelines and of those, most (80.6%) agreed with the recommendation [25]. It should be noted that these results were collected in the USA and thus from a different healthcare system. Women in our study might not have recalled correctly, if they were informed by their obstetrician about recommended GWG. Still, this study shows that postpartum women assign themselves to a pre-pregnancy BMI group that is too low and that they frequently have misconceptions about adequate weight gain during pregnancy. Even if they were informed, they did not correctly recall this information.

This is the first study conducted in Germany examining what percentage of postpartum women reporting that they received information about how much weight to gain during pregnancy. Information and actual knowledge about GWG were low in our sample. The existing strategies to implement IOM GWG guidelines are obviously not sufficiently strong to be effective. This warrants further investigations about the knowledge and opinions of the obstetricians on GWG in Germany and shows the need for increased patient support to help promote healthy weight gain during pregnancy.

This study protocol was reviewed and approved by the Local Ethics Committee of Hannover Medical School, approval number (9143_BO_K2020). The study was conducted according to the principles of the Declaration of Helsinki. Informed consent was waived by the Ethics Committee due to the use of retrospective and de-identified data. However, patients who completed the postpartum questionnaire part were required to give written informed consent.

All authors declare to have no financial or nonfinancial competing interests.

There was no funding for this study.

Conceived and conceptualized the study: L.B., M.Z., and P.H.; study design: L.B. and M.Z.; supervision: L.B., M.Z., and C.V.K.; analyzed the data: L.B. and M.Z.; contributed patient information/analysis tools: J.J.D. and D.L.M.S.; and contributed to the writing of the manuscript: J.J.D., D.L.M.S., L.B., P.H., C.V.K., and M.Z.

All data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding author.