Part 3 (2/2)

Several other studies which have looked at the impact of pica on pregnancy outcome appear to refute the dietary deciency theory. In certain societies pica is common. Luoba et al. (2004) found that 378 of the 827 women they studied in western Kenya were eating earth. Horner et al.

(1991), in a review of pica in the US, showed that the prevalence of pica among pregnant women from poor, rural and predominantly black areas declined between the 1950s and the 1970s but then remained constant.

They conclude that the evidence suggests that pica during pregnancy is a.s.sociated with anaemia and with maternal and perinatal mortality. Lopez et al. (2004) found a prevalence of 23 to 44 per cent in Latin America.

Rainville (1998) investigated the a.s.sociation of pica with two adverse pregnancy outcomes: low birthweight and preterm birth in a group of women from Texas, US. This study found a wide range and a high prevalence of pica if it was more broadly dened than usual; normally pica is used to refer to the craving for and practice of eating soil, clay or dirt. In 81 particular, the pica sample comprised those eating: ice, 53.7 per cent of their sample; ice and freezer frost, 14.6 per cent; other substances such as baking soda, baking powder, cornstarch, laundry starch, baby powder, clay or dirt, 8.2 per cent. Those reporting no pica as dened in this way only amounted to 23.5 per cent of the sample. Women in all three pica groups had lower iron levels at delivery but there were no differences in mean birthweight. In the UK, pica is rarer; our study (Pattison and Bhagrath, 2003) found only three women who experienced craving for non-food substances, all of whom came from non-European ethnic groups and none of whom actually ate the substances they craved.

So there is little evidence that pica attenuates dietary deciencies, though this may be the belief of women who practice it (Ukaonu et al., 2003); in fact it probably increases them. A meta-a.n.a.lysis of pica research found that ethnicity was the most important predictive variable (Simpson et al., 2000). Geissler et al. (1999) showed a strong a.s.sociated between pica and anaemia and iron depletion in women from Kenya. The women themselves described soil-eating as a predominantly female practice with strong relations to fertility and reproduction. They made a.s.sociations between soil-eating, the condition of the blood and certain bodily states. The beliefs women held about eating soil reect both a kind of dietary deciency thesis and the protection against illness thesis explored below. Geissler et al.

emphasise the importance of social and cultural contexts for how women interpret the experience of pregnancy. They conclude that pica is not simply a behavioural response to physiological need but rather that it is a rich cultural practice. Most western cultures regard pica as deviant and repulsive; Lopez et al. (2004) describe pica as adisorder'. Its practice is therefore secret and hidden and Henry and Kwong (2003) argue that pica is stigmatised in American society because of the meaning of dirt in that culture. However, they also argue that the consumption of vitamins and dietary supplements const.i.tutes a similar type of behaviour, done for similar reasons, albeit that it is regarded differently in health terms.

In contrast to pica, nausea is experienced by pregnant women of many cultures. In studies in the developed world, the majority of women report experiencing some nausea. A cross-cultural a.n.a.lysis by Flaxman and Sherman (2000) revealed 20 'traditional' societies in which morning sickness has been observed and seven in which it has never been observed.

As we discuss below, there is evidence that nausea affects food choice and is related to food aversions. However, the theory or belief that nausea and vomiting in pregnancy protect women from ingesting certain vegetables or foods that cause congenital abnormalities and other adverse outcomes of pregnancy is questionable. There have been a number of studies exploring the links between nausea, dietary intake and pregnancy outcome in terms of miscarriage or birthweight. Several of these have found no signicant a.s.sociation between them (Brown et al., 1997; Hook, 1978; Walker et al., 82 1985; Wijwardene et al., 1994) but Lee et al. (2004) found an a.s.sociation between even mild morning sickness and birthweight, and concluded that this was because it reduces dietary diversity and nutrient intakes. A study carried out in the US suggested that the women with the most extreme condition (hyperemesis gravidarum) had babies of lower gestational age and had longer antenatal hospital stays (Paauw et al., 2005).

In our own work (Pattison and Bhagrath, 2003, 2004), nausea and vomiting were the most common symptoms affecting food choice; most women responded by avoiding altogether foods they a.s.sociated with nausea.

Reasons that were cited for aversions in a study among Saudi women were smell (9.4 per cent), vomiting (28 per cent), diarrhoea (2.5 per cent), undesirable effect on foetus (7.8 per cent) and heartburn (18.7 per cent) (Al-Kanhal and Bani, 1995).

Dietary aversions usually occur earlier in pregnancy than do cravings and are frequently reported as being more severe. The most common aversions in US samples appear to be towards alcohol, coffee, meat and foods which have a distinct avour or smell, for example spicy foods or Italian foods (Hook, 1978; Pope et al., 1992). Pope et al. (1997) found that many of the adolescents they studied (66 per cent) experienced aversions during pregnancy towards previously liked foods. The most common aversions were to meats, eggs and pizza and led to decreased consumption of these foods. In our study too (Pattison and Bhagrath, 2003), 72 per cent of women developed aversions to food. The most commonly reported aversions were to meat (20 per cent) and spicy foods (20 per cent), though a small number (3 per cent) had developed an aversion to fruit and vegetables. Aversions were usually linked to nausea, with the smell or taste of these foods inducing nausea and/or being a.s.sociated with an incidence of vomiting.

This pattern of aversion suggests that rather than being a specic characteristic of pregnancy, aversions could reect a way in which women respond generally to foods that they a.s.sociate with nausea. It is well known that people generally can develop aversions to foods through a process of a.s.sociative learning. Whether or not the food was the cause of the nausea, the coincidental a.s.sociation of a bout of nausea or vomiting with a food is enough to create an aversion. In other words, nausea is created by hormonal changes during pregnancy but women interpret this symptom in the same way they would at other times and develop a taste aversion. Data to support this come from a study by Bayley et al. (2002) who studied the temporal a.s.sociation between the rst occurrences of nausea, vomiting, food cravings and food aversions during pregnancy. Of the women in their sample, nausea and vomiting were reported by 80 per cent and 56 per cent respectively, and food cravings and aversions by 61 per cent and 54 per cent respectively. Cravings and aversions were not related. There was a signicant positive correlation between week of onset of nausea and of aversions. In 60 per cent of women reporting both nausea 83 and food aversions the rst occurrence of each happened in the same week of pregnancy. No such a.s.sociation was found for cravings.

In the developed world, while pica is very uncommon, other cravings and aversions are common and rather prosaic. Pope et al. (1997) found that their US sample most frequently reported cravings for: sweets, especially chocolate; fruit and fruit juices; fast foods; pickles; ice cream; and pizza. Adolescents craving sweets during pregnancy consumed more sugar than those who did not crave sweets. Cravings generally resulted in increased intake, and aversions led to decreased food consumption. In our study (Pattison and Bhagrath, 2003), 62 per cent of women reported cravings. The most popular food craved was chocolate (32 per cent) and other foods craved were generally high carbohydrate and/or high fat foods, that is, bread, pasta, ice cream, chips, fruit, meat and what was generically termed 'McDonalds' (5 per cent of the sample). As in the study reported earlier (Pope et al., 1997), the women with cravings had increased their intake of these foods, with 91 per cent having consumed the food they craved in the 24 hours before they were interviewed.

It is clear then that cravings can have a signicant role in diet during pregnancy as they may increase total intake of food or change the proportion of foods eaten. However, cravings are not exclusive to pregnancy.

They are frequently reported in the general population and typically tend to involve foods high in sugar and/or fat, such as chocolate (Yanovski, 2003). So, can cravings in pregnancy be regarded as an extension of a normal experience?

There are two relevant theories as to why cravings develop and why they endure (Cepeda-Benito and Gleaves, 2001). The rst suggests that substances in the food supply a dietary imbalance. This imbalance may be caused in various ways, for example by dieting or by a nutritional de- ciency. This is the theory that most closely links to the dietary deciency hypothesis outlined above. So the increased need for calories in pregnancy, for example, would cause cravings for high calorie foods. The second type of craving theory is that of ncentive hypothesis' of craving. This suggests that cravings are a result of learning what foods produce feelings of wellbeing. This theory suggests that people have cravings for these particular foods because they have learned that the consumption of particular foods leads them to feel good. In psychological learning theory terms, they have learned to a.s.sociate the food with positive reinforcement. This reinforcement can either take the form of physiological or psychological reinforcement (Wise, 1988).

The incentive hypothesis is supported by research into chocolate craving.

In both the UK and the US, chocolate is widely reported to be the most commonly craved food. Michener and Rozin (1994) refuted the suggestion that this is because of the psycho-pharmacologically active substances in chocolate (e.g. caffeine), as they found that capsules containing the same 84 substances did not reduce cravings. It seems most likely that chocolate tastes and smells good to people. Rogers and Smit (2000) concluded that chocolate is simply a common example of the kind of food which people tend to a.s.sociate with pleasant taste, smell and texture, that is, one that is high in fat and sugar. Hill and Heaton-Brown (1994) looked at food cravings in healthy, non-binge-eating women. They found that the most frequently craved food was chocolate (high fat, high carbohydrate), with cravings for savoury foods, such as pizza, being much less frequently observed. In contrast to the accounts given by pregnant women, the food cravings reported by these women were seen as positive, pleasant, hunger-reducing, mood-improving experiences rather than reecting any biological need. So despite differences in the beliefs that pregnant and non-pregnant women have for their cravings, the cravings themselves are for similar types of food. Furthermore, Crystal et al. (1999) found a signicant a.s.sociation between experiencing cravings and aversions prior to pregnancy and experiencing cravings and aversions during pregnancy.

A number of more general studies suggest that women's diet during pregnancy is strongly inuenced by their tastes and eating habits before pregnancy. Mathews and Neil (1998) studied 774 women in the early stages of pregnancy and found that their dietary intake was very similar to that of non-pregnant women and accordingly they were short of some nutrients thought to be important for foetal health. Perhaps the most striking results in this regard come from a qualitative study of the diets of pregnant teenagers for the Maternity Alliance and the Food Commission in the UK (Burchett and Seeley, 2003). They gave detailed accounts of the reasons why they did not eat foods that they regarded as healthy, and the most common reason, given by nearly half of the teenagers, was dislike of that foodstuff. Cost was also a factor for a fth of them and a number also said that the foods were unfamiliar or not offered in their homes. Other reasons for avoiding healthy foods were the effort required to buy them and cook them.

In summary, most of the research on aversions and cravings in pregnancy has stemmed from the a.s.sumption that the dietary behaviour of pregnant women is a direct result of pregnancy. So aversions and cravings are a.s.sumed to result from biological processes which protect women from infection and restore dietary deciencies. Although there may be some merit in this approach, it ignores the lifetime of experience that women have had with food, particularly in relation to cravings. So is this a time when women feel less restrained in their eating?

Restrained and unrestrained eating Unlike diet in pregnancy, the concept of dietary restraint has been widely studied by psychologists. Dietary restraint refers to the tendency to restrict 85 food intake, usually in order to lose weight, or to maintain slimness. It is a volitional but stable behaviour. Herman and Polivy (1983) developed theboundary' model of eating behaviour, which suggests that two physiological boundaries determine when people start and stop eating: hunger and satiation. However, restrained eaters have another self-imposed boundary, which overrides the other boundaries the diet boundary, that is, the amount of food (or calories) that restrained eaters believe they should consume. This diet boundary overrides the normal hunger and satiation boundaries. Dietary restraint is common in women in western cultures as evidenced by the high proportion of women who report dieting at any one time. It is beyond the scope of this book to give a detailed account of the impact of pregnancy on severe eating disorders. Here we will look at the evidence that what might be termed 'normal' dieting behaviour before pregnancy has an impact on what and how much women eat during pregnancy. Pregnancy might be a time when social pressures for slimness could be expected to be relaxed, thus resulting in reduced weight concern despite an increase in body size. Women may therefore be less restrained in terms of what and how much they choose to eat, causing weight gain to be higher. On the other hand, restrained eaters may remain subject to the cultural pressure to be slim and continue or even increase their dieting behaviour. Similarly, restrained eaters may be happy with their pregnancy shape, as it is something apart from their normal experience, or restrained eaters may see the weight and size gained in pregnancy as distasteful. The evidence on both these issues is contradictory.

Davies and Wardle (1994) evaluated body image, body satisfaction and dieting behaviour in pregnancy, expecting women to feel less social pressure to be slim. Pregnant women certainly had a lower 'drive for thinness', had lower body dissatisfaction and rated themselves as less overweight than non-pregnant comparisons. However, they showed similar preference for size of gure to non-pregnant women. These ndings suggest that pregnancy is a time of relaxation in concerns about weight, but that this change is temporary and does not override women's general beliefs about their ideal weight and body shape. Davies and Wardle's ndings chime with our study (Pattison and Bhagrath, 2003).

We did not measure dietary restraint directly; however, the women we interviewed were signicantly more likely to be satised with their pre-pregnancy shape than current shape. And those who were more satised with their pre-pregnancy shape were more condent they could regain it. This suggests that the women who had experience of successful weight control before pregnancy were condent in their ability to exercise such control again.

Clark and Ogden (1999) investigated the role of dietary restraint in mediating changes in eating behaviour and weight concern in pregnancy.

They also compared pregnant and non-pregnant women. The pregnant 86 women reported eating more, showed lower levels of dietary restraint and were less dissatised with their body shape than the non-pregnant group.

They also showed higher eating self-efcacy, that is, the belief that one can control one's own eating. The pregnant women rated themselves as less restrained in their eating behaviour than they had been immediately before their pregnancy and nearly half reported eating more. Clark and Ogden also found that the previously restrained eaters, when pregnant, rated themselves as signicantly less hungry and having greater eating self-efcacy than the non-pregnant restrained eaters. They were comparable in these regards to non-restrained eaters. The results showed no effect of restrained eating on weight change. Clark and Ogden concluded that for women who normally restrain their eating, pregnancy both legitimises an increased food intake and removes previous intentions to eat less.

But other studies contradict these ndings. For instance, Conway et al.

(1999) studied dietary intake and weight gain during pregnancy in relation to dietary restraint in a longitudinal study of women from early to late pregnancy. In their study, current dietary restraint was measured (i.e.

restraint employed during pregnancy). They found that restrained eaters were less likely to experience weight gains within the recommended range for their pre-pregnancy body ma.s.s index (a ratio of height to weight). This went either way such that some gained more weight and some less weight than recommended. DiPietro et al. (2003) studied pregnant women's weight-related att.i.tudes and behaviours in relation to several psychological and social characteristics. This was not a longitudinal study, rather women's att.i.tudes about weight gain were a.s.sessed once at 36 weeks of pregnancy Several variables had been a.s.sessed prior to this, namely anxiety, depression, social support, emotionality and perceived stress (pregnancy-specic and non-specic). Twenty-one per cent of the women were restricting their food intake in some way during pregnancy. The women who reported more restrictive behaviours were more anxious, depressed, angry, stressed and felt less uplifted about their pregnancies in general. Those women who were more positive about their bodies during pregnancy felt better about their pregnancies in general. They also were less depressed and felt less angry. On the other hand, women who were self-conscious about their pregnancy weight gain felt more ha.s.sled by their pregnancies and felt greater anger, though they also reported more support from their partners. Women's feelings about their weight gain were not related to their body ma.s.s index before their pregnancy. The authors noted that negative att.i.tudes about weight gain existed among women who gained weight within the recommended ranges. All this suggests that women's att.i.tudes to weight gain during pregnancy are related to their general feelings about their pregnancy and psychological health rather than to their general feelings about their weight and their eating habits during pregnancy. A number of other studies have also found that women with a 87 history of dieting are less satised with their bodies during pregnancy than those who do not normally diet (Abraham et al., 1994; Fairburn and Welch, 1990; Wood Baker et al., 1999).

So why do different studies have contradictory ndings on the inuence of women's dietary restraint before pregnancy? One obvious difference between studies is whether they involve women who restrained their eating before pregnancy (e.g. Clark and Ogden, 1999) or refer only to women who restrained their eating during pregnancy (e.g. Conway et al., 1999).

These may well represent different groups of women, or the latter may be a subset of the former. However, other reasons for contradictory ndings may lie in more recent theories of dietary restraint.

Recent work has established that dietary restraint itself is not a unitary phenomenon and can be applied in different ways. Joachim Westenhoefer proposes that there are two types of restraint: exible and rigid. These two styles may lead to different strategies for dietary change during pregnancy.

Flexible restraint involves adaptation to the current circ.u.mstances, so while food intake is carefully controlled overall, if large amounts of food, or high calorie foods, are eaten on one occasion, this is compensated for by eating less on a later occasion. Rigid restraint on the other hand is an all or nothing' approach. Rigidly restrained eaters tend to diet frequently, but if they do eat foods that they feel they should avoid, then they do not compensate by eating less. These are the cla.s.sic type of restrainers cla.s.sied by Herman and Polivy (1983) as exhibiting thewhat the h.e.l.l' effect. One implication of this for diet during pregnancy is that rigidly restrained women, once they have veered away from a weight control diet, may be expected to give up weight control entirely. The main reasons why rigid restrainers may stop restraining what they eat are the lack of social pressure to be slim and the sanction of eating forbidden foods because of cravings. Herman and Mack (1975) discovered that an important characteristic of restrained eaters is that they can be induced to eat more than non-restrained eaters if they rst consume apreload' usually a sweet high calorie drink. However, Westenhoefer et al. (1994) found that exible restrained eaters ate less following eating the preload than did rigid restrained eaters. Presumably this mimics their normal eating patterns.

So exible eaters make up for eating a high calorie food by eating less or low calorie foods, whereas once rigid eaters breach their 'diet boundary'

they do not seem able to control their eating. It is noteworthy that most craved foods during pregnancy have high sugar content and are high in calories. If rigidly restrained eaters eat craved foods one would predict that this would act like a preload, and they would not compensate for it.

Flexible restraint is a.s.sociated with the absence of overeating more generally and low levels of depression and anxiety (Smith et al., 1999). If the partic.i.p.ants in different studies of eating during pregnancy involve different types of restrained eaters, or a mixture of the two, they should 88 nd different patterns of restraint and different levels of weight control.

Unfortunately, studies of dietary change in pregnancy have not provided conclusive evidence on this yet.

Advice, recommendations and food scares During the last century the majority of medical authorities recommended that weight gain during pregnancy should not exceed 9.1kg, primarily to prevent the development of maternal toxaemia, foetal macrosomia and caesarean deliveries. These recommendations increased to 11.4kg in the 1970s because it was felt that insufcient weight gain could contribute to premature births and to low birthweight babies born at the expected date.

However, in 1990, an inuential report from the Inst.i.tute of Medicine in the US (U.S. Inst.i.tute of Medicine, 1990) recommended weight gain ranges of 11.415.9kg with the primary goals of improving infant birthweight and ensuring the best outcome for the mother. These weight gain recommendations vary according to the pre-pregnancy weight to height ratio as measured by body ma.s.s index (BMI). However, a signicant number of normal weight women and an even greater proportion of overweight women in the US exceed these guidelines (Abrams et al., 2000). In fact, published studies suggest that only 3040 per cent of women have weight gains within the Inst.i.tute of Medicine's recommended ranges, with some gaining less weight than recommended but most gaining more weight than the guidelines suggest they should (International Federation of Gynaecology and Obstetrics, 1993).

In countries such as the US and UK, midwives and other health professionals see it as part of their role to offer advice on diet and weight gain, so why is this advice apparently not acted on? Is it so difcult to follow? As we have discussed above, there are various factors which inuence dietary behaviour which may lead to weight gain above or below guidelines, such as dietary beliefs, cravings and aversions. However, the nature of the advice that women receive and their interpretation of that advice may also inuence behaviour. As we also discuss in relation to physical activity in the next chapter, advice given by midwives and publications for pregnant women is often vague, recommending ahealthy diet'. Here, as in the general population, if health education messages do not t lay health models, they are less likely to be taken up (Ikeda, 1999; Lupton and Chapman, 1995). In other words, the form and content of the advice, the language used and directions for how to act on the advice have to be understood and integrated into what the woman knows and believes.

For example, American adolescents interviewed by Skinner et al. (1996) said they would prefer to watch a video with atalking baby' or teenage actresses presenting the information than read a leaet or book. They also wanted more information about food than nutrients.

89.It should also be remembered that health professionals are not the only sources of advice; women have access, to varying degrees, to information from family, friends, magazines, books, television and other media and increasingly to the internet. For example, Lewallen (2004) found that family members were a common source of advice for low-income pregnant women in the US, and in our study of a varied group of women in the UK (Pattison and Bhagrath, 2003), less highly educated women and women from minority ethnic groups were less likely to use books, magazines and the internet. These variations are important because the type and content of advice from different sources vary and may conict.

The majority of women in Norman and Adams' (1970) study reported that they had made changes in their diet because of dietary advice from health professionals. Orr and Simmons (1979) a.s.sessed patients'

satisfaction with dietary advice received and found that the majority of patients expressed satisfaction with the amount of information received. A study by Cogswell et al. (1999) revealed that reported advice during pregnancy is strongly a.s.sociated with actual weight gain. However, about half of the women in their study reported having received no advice, or inappropriate advice from healthcare professionals about weight gain during pregnancy: Overweight women were more likely to report having received advice to gain weight greater than the recommended amount during pregnancy. What these studies have in common is that the reported behaviour ts in with the reported advice. Thus, women have created a narrative which is internally consistent, sanctioning behaviour by providing an account of ofcial advice.

In our study (Pattison and Bhagrath, 2003) 30 per cent reported having received no advice from their midwife or general pract.i.tioner, something we return to in the discussion of advice on activity in Chapter 6. The majority of women who remembered receiving advice said they would have liked more than simply being advised to eat healthily' and explanations of why certain foods should be avoided. Women who were more highly educated and expecting their rst child were most likely to seek out alternative sources of information, particularly books, magazines and the internet. Often, nutritional advice is given in antenatal clinics, however not all women actually attend these clinics and the women who do are usually found to be of higher than average socioeconomic, educational and occupational status, characteristics which are also found to be a.s.sociated with already better than average nutritional knowledge and dietary practices (Fowles, 2002). This implies that populations that are more in need of additional advice and information are less likely to receive it.

Midwives in the UK no longer specify optimum levels of weight gain for most women, and for several years women were not weighed. Fowles (2002) found that most women had inadequate general nutritional knowledge and therefore, hardly surprisingly, their dietary intake did not meet all 90 the nutritional requirements of pregnancy. Women are usually encouraged to improve their diet during pregnancy but information on how to improve diet is vague. Most advice mentions fresh fruit and vegetables or eating abalanced diet'. However, this kind of advice, to simply eat 'more healthily'

throughout pregnancy, is not sufcient if women do not have the knowledge for it to act as a prompt to particular behaviours. Furthermore, as we have discussed above, traditional beliefs about what const.i.tutes a healthy diet during pregnancy are likely to be at odds with current nutritional theories.

The vagueness of advice on positively improving diet during pregnancy is in stark contrast to advice on what should be avoided. Often starting as food scares in newspapers, or on television and radio news programmes, advice about avoiding hazardous foodstuffs is often extremely specic. As we said in the introduction to this chapter, pregnant women often nd themselves the focus of food scares. They may be a specic focus of information because a link has been made between a food and foetal or, more rarely, maternal health. They may also be targeted because they are perceived as vulnerable to health hazards. Women are more vulnerable, of course, during pregnancy because of their suppressed immune system (necessary so their body does not reject the foreign tissue of their baby).

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