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The evaluation of an intervention aimed at improving dietary intake during pregnancy, optimizing gestational weight gain, glycemic levels and birth weight, and avoiding unnecessary postpartum weight retention.

All Cree women receiving prenatal services prior to 26 weeks' gestation in the communities of Chisasibi, Wemindji, Waswanipi and Mistissini between July 1995 and January 1997 were eligible.

Women with pregestational diabetes.

Recruitment Women recruited between July 1995 and March 1996 served as controls, whereas women identified between April 1996 and January 1997 made up the intervention group.  All participants gave signed consent.

Design Prospective Cohort 

Blinding used (if applicable) Not described

Intervention (if applicable)  The intervention was based on the social learning theory.  The table below outlines strategies and activities used in the intervention.

Dietary advice was related to improving the intake of dairy products and fruit and vegetables, while decreasing the intake of high-energy foods with little nutritional value such as soft drinks, fruit drinks and french fries and staying within guidelines for weight gain during pregnancy.

People	Strategies	Activities
Nutritionists	Modeling	Local radio broadcasts about healthy eating in pregnancy
Cree Health Workers	Skill Training	Pamphlets about nutritional choices and encouraging breastfeeding
	Contracting	Supermarket tours and cooking demonstrations
	Self-monitoring	Exercise/walking groups
		Individual Counseling

A baseline questionnaire provided demographic information, a brief prenatal history and information about smoking.  Dietary data were obtained by 24 hour recall at one time point between 24 and 30 weeks gestation and at 6 weeks post-partum.  Physical activity was measured at the time of the 24 hour diet recalls by a questionnaire related to usualy daily activities in both the village and the bush.

Infant birth weight and type of delivery were obtained from the medical charts.  The ratio of the measured birth weight to median birthweights specific to gestational age was used to compare birthweight among the Cree with non-Aboriginal standard.

Statistical Analysis  Participants were compared with nonparticipants living in their communities at the same time.  All participants were included in the intention-to-treat approach to the analysis.  Mean nutrient intakes, birth weight, birthweight ratio, gestational age, ratio of weight gain, glycemic level on the glucose screen and postpartum weight retention were compared for the treatment groups by independent t-tests, after adjusting for normality where warranted.  Log transformation was used to normalize pregravid weight, BMI and postpartum weight.  The sample size was sufficient for 80% power, using a 2-sided t-test to detect differences in birth weight of 215 g, energy intake of 1396 ks (12.6%), plasma glucose level of .74 (10%) mmol/L, rate of weight gain of .1 kg per week and postpartum weight retention of 1.9 kg.  It was not possible to have a sufficiently large sample size to detect differences in GDM rates.

Timing of Measurements  Physical activity and dietary information was collected between 24 and 30 weeks gestation and at 6 weeks postpartum.  A 50 g oral glucose screen test was performed between 24 and 30 weeks gestation, followed by a 100 g OGTT if the screen value was greater than 7.8 mmol/L. 

The rate of weight gain was calculated from 20 weeks to delivery (kg/week).  Recalled pregravid weight was used if it was within 5 kg of documented weight up to 10 weeks' gestation and within 7 kg of documented weight between 10 and 14 weeks gestation, otherwise the earliest prenatal wt (<14 weeks) was used.  Pregravid weight was recorded from the women's recalled weight (69%), from an early prenatal visit (23%) or was considered missing (8%).  Postpartum weight retention was calculated as measured weight at approximately 6 weeks post partum minus pregravid weight.

Women in the intervention group were seen at least monthly.

Dependent Variables

• Improved dietary intake
• Optimal gestational weight gain, glycemic levels and birth weight
• Avoiding unnecessary postpartum weight retention

Independent Variables 

• Diet and activity intervention 

Control Variables  Adjustment for intitial BMI, age and smoking appear to have been made for comparing infant birth weight, otherwise not described.

 

Initial N: 219, 107 in the control period and 112 in the intervention period

Attrition (final N): Variable, not described

Age: 23. 8 +/- 5.86 years for controls, 24.3 +/- 6.29 years - not significantly different

Ethnicity: Cree

Other relevant demographics: Not described.

Anthropometrics

• Prepregnancy weight: 78.9 kg (+17.54) controls, 81 kg (+19.46) intervention
• Height: 163.2 cm (+5.71) controls, 162.0 cm (+5.04)
• BMI: 29.6 (+6.45) controls, 30.8 (+6.85)
• Gestational age at recruitment: 17.1 weeks (+7.06), 18.5 weeks (+6.92)

Location:  Cree communities

 

The intervention and control groups did not differ at baseline regarding their mean age, mean prepregnancy weight and mean gestational age.

The intervention did not result in differences in diet measured at 24-30 weeks' gestation, rate of weight gain over the 2nd half of pregnancy or plasma glucose level between 24 and 30 weeks.   Mean birth weights were similar as was maternal weight at 6 weeks post partum.

The only changes in dietary intake were a reduction in caffeine during pregnancy and an increase in folate post partum.

Variable	N	Control Group	N	Intervention
Weight gain (kg/wk)	96	.53 (.32)	104	.53 (27)
Weight gain (kg/wk) BMI <29	49	.63 (.32)	51	.62 (.27)
Weight gain (kg/wk) BMI >29	47	.44 (.30)	53	.44 (.24)
Plasma glucose, mmol/L	87	7.21 (2.09)	97	7.43 (2.10)
Gestational age at delivery, wk	103	39.56 (1.87)	106	39.53 (3.42)
Birth wt, g	103	3741 (523)	106	3686 (686)
Birth weight > 4000 g (#, %)	103	31, 30.1%	106	37, 34.9%
Birth weight < 2500 g (#, %)	103	2, 1.94%	106	3, 2.83%
Birth weight ratio	103	1.15 (.18)	106	1.15 (.16)
C-section (#, %)	103	13, 12.62%	106	15, 14.15%
Postpartum weight, kg	75	88.1 (16.8)	62	86.4 (19.0)

Other Findings 

In the control group, there were 10 confirmed cases of GDM and an estimated additional 4 cases among those with a high glucose screen and no OGTT for a prevalence of 14.7%, 95;(7.58% - 21.8%).  In the intervention group, there were 15 confirmed and 3 estimated cases of GDM for a prevalence of 16.2%, 95; (9.15%-23.3%).   

A cross sectional analysis, controlling for the known effect of age on body weight by analysis of covariance, indicated that nulliparous women had a mean prepregnancy weight of 76.1 kg as opposed to 82.1 kg in parous women (p = .049).

Breast feeding at 6 weeks post partum was prevalent in both groups, with 83% of women in the control group and 87% of women in the intervention group breast-feeding their infants.  

During the postpartum period, energy intakes were higher than during pregnancy (p<.05). 

The addition of 2 nutritionists was viewed as positive by the communities, but the intervention did not change any of the outcome measures. 

Energy intakes were high at 142 kJ/kg compared with recommended intakes of 105kJ/kg for overweight women and 146 kJ/kg for women of normal weight.  The dietary intake data indicated a direct correlation with weight gain.

The large amount of retained weight at 6 weeks post partum compounds the problem of being overweight and the high risk of type 2 diabetes in this population.

The reasons why the intervention was not successful have been reflected upon by all involved.  Discussions with women in the communities made it clear that being plump is desirable, whereas physical activity during pregnancy is not considered desirable, despite the fact that the older community members report that inactivity dring pregnancy is a recent phenomenon.

One 24 hour recall is not likely to be sufficient to capture true dietary intake.  The results might have been more robust had they obtained more recalls and averaged the results.

Why the reported N changed and the reason for missing data is not described.

Six weeks is a very short period in which to measure postpartum weight loss.