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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 7  |  Issue : 1  |  Page : 37-42

Maternal knowledge of the impact of obesity on complications relevant to obstetric anesthetic care


1 Department of Anaesthesia and Perioperative Medicine, North Shore Hospital, Auckland, New Zealand
2 Department of Anaesthesia, Royal Brisbane and Women's Hospital, Queensland, Australia
3 Department of Anaesthesia and Pain Medicine, King Edward Memorial Hospital, Perth, Western, Australia
4 Biostatistics and Research Design Unit, Women and Infants Research Foundation, Perth, Western Australia, Australia

Date of Web Publication1-Jun-2017

Correspondence Address:
Laura F McDermott
Department of Anaesthesia, Royal Brisbane and Women's Hospital, HERSTON, QLD, 4006
Australia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2249-4472.194295

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  Abstract 

Background: The number of overweight adults in Australia has more than doubled in 20 years and 50% of pregnant women in Australia are overweight. This study investigated whether pregnant women are aware of the peripartum obstetric and anesthetic risks conferred by obesity. Methods: A sample of 180 antenatal women attending an obstetric tertiary referral hospital were surveyed to identify the level of knowledge about the effect of obesity on medical, obstetric, and anesthetic outcomes, using a 23-item questionnaire. Correct responses were expressed as a percentage and comparisons, based on maternal characteristics including body mass index (BMI), performed using Mann–Whitney and Kruskal–Wallis tests for continuous outcomes and the Chi-square test for categorical outcomes. Logistic regression analysis was conducted to evaluate the maternal characteristics predictive of scores below the 50th percentile. Results: The median percentage of correct answers for all participants was 39% (interquartile range: 30–52%). More correct responses were obtained to questions about medical and obstetric complications. pre-pregnancy BMI ≥ 30 kg/m2, nulliparity, and no tertiary education were significant predictors of scores below the 50th percentile in the survey. Knowledge of the effects of obesity on anesthetic complications did not appear to be influenced by maternal age, ethnicity, or planned mode of delivery. Conclusion: The median number of correct answers was less than half, with women with a BMI < 30 kg/m2 being less knowledgeable. Knowledge about anesthetic problems and risks was less than that about medical and obstetric issues.

Keywords: Anesthetic, complications, maternal knowledge, obesity, obstetric


How to cite this article:
Tulp MJ, McDermott LF, Paech MJ, Nathan EA. Maternal knowledge of the impact of obesity on complications relevant to obstetric anesthetic care. J Obstet Anaesth Crit Care 2017;7:37-42

How to cite this URL:
Tulp MJ, McDermott LF, Paech MJ, Nathan EA. Maternal knowledge of the impact of obesity on complications relevant to obstetric anesthetic care. J Obstet Anaesth Crit Care [serial online] 2017 [cited 2019 Dec 11];7:37-42. Available from: http://www.joacc.com/text.asp?2017/7/1/37/194295


  Introduction Top


Approximately 50% of Australian women who become pregnant are either overweight (body mass index [BMI] 25–29.9 kg/m 2) or obese (BMI ≥30 kg/m 2).[1],[2] Many women are unaware of the current recommendations surrounding gestational weight gain [3],[4],[5] or of the implications of obesity for fertility, obstetric complications and anesthetic risks.[6],[7]

The literature does not appear to have explored the level of detail to which women of childbearing age have been educated with respect to specific obstetric analgesic and anesthetic risks associated with obesity. Obesity is associated with more than 50 medical, obstetric, and anesthetic complications during pregnancy.[8],[9] Many obstetric providers are knowledgeable about the potential anesthetic complications, yet these are rarely discussed with patients.[8] Several professional bodies recommend that morbidly obese women are assessed and advised at antenatal anesthetic clinics,[10],[11],[12] but the educational value of such a consultation may be low.[7]

We designed a survey related to knowledge about the potential impact of obesity on factors of anesthetic relevance during pregnancy, labor, and delivery. The objective was to ascertain the levels of knowledge and to determine whether there was a need to develop strategies to educate and counsel women, particularly those who are already obese prior to pregnancy.


  Methods Top


We developed a 23-item questionnaire for this survey and administered it to antenatal pregnant women attending a large multicultural obstetric tertiary referral hospital delivering approximately 6000 women per annum, of whom approximately 15% have a BMI ≥35 and 10% have a BMI ≥40 kg/m 2.

The study was approved by the Institutional Ethics Committee (2014023EW) and was internally funded by the Department of Anaesthesia and Pain Medicine where this study was performed. Participants were recruited from the antenatal clinic, diabetic clinic, maternal-fetal assessment unit, hospital ward, day surgery unit, or on-site midwifery-model family birth center. Antenatal women who were present at these locations, available at the time when approached and who provided written informed consent, took part in this survey. Exclusion criteria were women of <18 years, those who needed an interpreter, and those with mental illness or disability. The study was conducted between July and November 2014.

The survey questionnaire was distributed by the research team, which included midwives, trainee and specialist anesthetists. The survey information sheet explained the purpose of the survey and gave participants a definition of obesity by stating that “Obesity is measured using the Body Mass Index (BMI) which is calculated by dividing weight in kilograms by height in metres squared. Obesity is defined as a BMI of 30 or above. For example, a woman who is 1.64 m tall and 82 kg in weight would have a BMI of 30, which falls into the obesity range.”

Obesity was categorized using BMI and calculated as described above using the World Health Organization definition of a BMI equal to or more than 30. Ideally, this value is based on pre-pregnancy weight, however if this is not available or unknown, the weight at the first antenatal consultation should be used.[12] For the purpose of this study, pre-gestational and current BMI values were obtained from the participants. However, pre-gestational weight was used to analyze and categorize the patients into obese and non-obese subgroups.

Questions were directed toward the possible effects of obesity on medical or obstetric risks, complications of epidural analgesia during labor, and risks associated with peripartum anesthesia, the stems being “If you require care by an anaesthetist (a specialist doctor who provides pain relief in labour and anaesthesia for surgery, such as for caesarean birth), which of the following do you think are influenced by obesity during labour and delivery?” [Appendix 1 - Questions 1–9]; “If you require care by an anaesthetist (a specialist doctor who provides pain relief in labour and anaesthesia for surgery, such as for caesarean birth), which of the following do you think are influenced by obesity at the time of surgery?” [Appendix 1 - Questions 10–15]; and “of the following general medical or obstetric problems, which of the following do you think are at increased risk with obesity during pregnancy, labor, or delivery?”[Appendix 1 - Questions 16–23]. Responses were sought on a four-point scale of the stem being “more likely,” “less likely,” or “unchanged.” An additional “I don't know” option was also available. A best correct answer to each question was predetermined by consensus of the authors based on literature review. When evidence was equivocal, “don't know” was deemed to be the correct response. [Additional file 1]

The convenience sample size of 150 was considered sufficient to obtain statistical parameters with an approximate error margin of 8%, with 80% power, and alpha of 0.05. To allow for incomplete data, the sample size was increased to 180. Data were summarized with median, interquartile range (IQR) and range (R); or frequency distributions, for continuous and categorical data, respectively. Correct responses to the survey questions were summed and expressed as a percentage of correct responses. Comparisons of correct responses based on maternal characteristics such as body habitus, age, parity, ethnicity, and education were made using Mann–Whitney and Kruskal–Wallis tests for continuous outcomes and the Chi-square test for categorical outcomes. Logistic regression analysis was conducted to evaluate the maternal characteristics predictive of scores below the 50th percentile on the obesity survey and summarized with odds ratios and 95% confidence intervals. SPSS v20 statistical software (IBM Corp., Armonk, NY, USA) was used for data analysis and P values < 0.05 were considered statistically significant.


  Results Top


One hundred and eighty women consented and answered the questions. Patient characteristics are shown in [Table 1]. The majority (78%) of the participants were <35 years of age and were scheduled for elective cesarean delivery (56%). The largest proportions of women were Caucasian, multiparous, and tertiary educated. Twenty-nine percent of the study population was obese as per pre-gestational weight.
Table 1: Demographic characteristics (n=180)

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Answers to the questions are shown in [Table 2]. The median percentage of correct answers for all participants was 39% (IQR 30–52%). Prepregnancy BMI ≥30 kg/m 2, nulliparity, and no tertiary education were the significant predictors of scores below the 50th percentile [Table 3]. Knowledge of the effects of obesity on obstetric and anesthetic complications did not appear to be influenced by maternal age, ethnicity, or planned mode of delivery [Table 3].
Table 2: Responses

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Table 3: Maternal characteristics associated with scores lower than the 50th percentile

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  Discussion Top


In this study, a random sample of pregnant antenatal women planning to deliver at our institution was surveyed regarding their knowledge about practical issues, risks and complications associated with obesity in pregnancy. The focus was on events relevant to anesthetic care during labor and operative delivery. Very few questions were answered correctly and women who were obese appeared to be less knowledgeable.

The knowledge of women about the risks of medical conditions and adverse pregnancy outcomes associated with obesity is generally poor.[6],[7] This was also the case in this survey, however the highest percentage of correct responses related to questions pertaining to medical disorders and obstetric complications, rather than to those about the complications of analgesia and anesthesia. Pregnant obese women are at risk of hypertension, gestational diabetes, thromboembolism, infection, congenital abnormalities, preterm birth, stillbirth, fetal macrosomia, prolonged labor and cesarean delivery, neonatal intensive care admission, and perinatal death.[1],[2],[13] In addition, there are a number of anesthetic risks and complications that are increased among women of high BMI.[8],[9],[14] These include more difficult, failed and repeat neuraxial labor analgesia (due to difficult placement and higher rates of epidural catheter dislodgement).[9],[15],[16] Nevertheless, early epidural catheter placement during labor is recommended for morbidly obese parturients [14],[16] because the complications of general anesthesia, which are over-represented as the causes of anesthetic-related death and serious morbidity in maternal mortality and morbidity reports, also appear to be further increased among morbidly obese women compared to normal body weight women.[17],[18],[19],[20],[21] It has been suggested that obese women are at a higher risk of aspiration of gastric content, hypoxic events secondary to difficult airway management, intraoperative hypotension, and maternal blood loss.[13],[18],[22],[23] Neuraxial anesthesia is more difficult, takes longer to perform, and is more likely to prove of insufficient duration during surgery, consequently requiring conversion to general anesthesia.[22],[23],[24] Only half the women we surveyed were aware that anesthesia was likely to be more complicated in obese women, with few appreciating the technical difficulties involved in management or the pathophysiological derangements that predispose obese patients to adverse events and outcomes. In a cohort of obese pregnant women, Eley et al. reported that only a fifth considered that their health was at a greater risk during pregnancy compared with other women.[7]

Limitations of this study include the small sample size and a single institution demographic sample. While the definition of obesity was given in the study patients' information form, the participant's perception of what represents obesity may have been different as the educational and cultural influences on the perception of obesity were not explored in this study. The subgroup of women surveyed who were obese was too small to permit valid statistical comparisons with responses to individual questions from nonobese women. While the primary goal of this survey was to determine the level of education in a population of pregnant women, sampling a broader population of women of childbearing age or sampling sufficient numbers of women meeting the criteria for obesity or non-obesity would be useful.

Another limitation is that the “correct” answer ascribed to some questions is arguable, based on there being multiple components to the issue or risk being evaluated. For example, the obese parturient, despite having lower pharmacological requirements for epidural analgesia during labor,[25] may need more interventions. Tonidandel et al. compared the medical records of 230 patients weighing >136 kg with those of matched controls weighing <113 kg and found a higher number among the more obese for earlier epidural placement, re-dosing the epidural, a higher rate of epidural resiting, and more local anesthetic use.[9] Vricella et al.[23] found a higher rate of neuraxial failure among a retrospective cohort of women having cesarean deliveries, but Bamgbade et al.[24] did not find a significant difference in spinal anesthetic failure at cesarean delivery. The risk of accidental dural puncture appears increased by obesity, but the chance of subsequently developing a postdural puncture headache may be reduced.[26],[27] With regard to the time to recover after general anesthesia, the evidence is uncertain, with differences in the kinetics of intravenous and inhalational anesthetics failing to provide a definitive answer except that any change is likely to be clinically unimportant.[28]

This survey suggests that the medical profession has a lot of work to do in educating the public about potential complications of obesity and the impact on health care during pregnancy. Despite the fact that outcomes have improved in obese parturients over the past 20 years,[9] this may be because anesthetists, rather than the public, have become more aware of the issues. Discussion of the implications of obesity for pregnancy-related disorders and obstetric outcomes is within the domain of the general practitioner and the obstetric care provider, but discussion of anesthetic issues is likely to be more effective if undertaken during an anesthetic consultation.[7],[8] Local policies should be in place with regard to advice and help with weight gain limitation and with respect to patterns of referral of obese women to anesthetic services because it is logistically impossible for anesthetic departments to review all pregnant women who are obese. This type of consultation has been shown to help morbidly obese pregnant women decide on labor analgesia plans without increasing anxiety.[7] However, for some women the discussion is a negative experience, particularly if not conducted with tact or if the information provided is inconsistent with previous misinformation from other healthcare workers.[7]

Although one-third of the women who completed this survey were obese, their knowledge was very poor. It is likely that these women represent those most in need of counseling prior to pregnancy and during the antenatal period. Increasing women's awareness of the complications associated with obesity that increase their health risks is the first step in education that might address the rapidly increasing prevalence of obesity in pregnancy.[29] Failure to address this burgeoning problem compounds unrealistic patient expectations, disappointments and compromises the provision of informed consent. In the longer term, non-obstetric evidence suggests that healthy lifestyle choices reduce the incidence of chronic disease [30] and in this setting, ultimately defray the increasing cost of maternity care.

Obstetric obesity is unlikely to remain a problem confined to affluent nations because developing nations where Western lifestyles have been adopted also have many women at risk. Such countries are likely to be under-resourced to manage these high-risk patients and may be reluctant to draw attention to the risks. Addressing these issues is a task for individuals and governments alike. Healthcare systems need to emerge from a long period of unwillingness to label women as obese and of avoiding addressing the implications of obesity. Strategies to politely educate and advise women, preferably prior to conception, about the problems posed by obesity in pregnancy and to implement evidence-based approaches that support weight loss, healthy weight gain during pregnancy and return to nonobesity postpartum, need development.

Acknowledgments

  • Contributions that need acknowledgment but do not justify authorship: We wish to thank the research midwives Mrs. Desiree Cavill and Mrs. Michelle Porteous for their help in the conduct of this study.


Financial support and sponsorship

This study was internally funded by the Department of Anaesthesia and Pain Medicine at Kind Edward Memorial Hospital.

Conflicts of interest

There are no conflicts of interest.

 
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