Objectives. The Pregnancy, Nutrition & Diabetes (PND) study aimed to evaluate the
dietary status of urban Black pregnant women attending the Antenatal Clinic at the Charlotte
Maxeke (Johannesburg General) Hospital. In addition, the study investigated the effects of
maternal dietary intake and hormonal levels during pregnancy on fetal growth, birth size and
the early postnatal development of risk factors for future Type 2 diabetes. The study analysis
precedes a detailed description of the study population, including its comparison with other
populations.
Methods. 126 women were enrolled in the study before 24 weeks of gestation. Twice
during pregnancy (weeks 20-24 and 30-36, visits V1 and V2) and approximately six months
after the delivery (visit V3), volunteers participated in a standard 75 g oral glucose tolerance
test (OGTT). Blood pressure, anthropometric and socio-demographic data were taken and a
food frequency questionnaire was administered at each visit. The daily maternal intakes of
total energy and macronutrients expressed as a % of total energy intake (%E) were calculated
and further evaluated. A comparison with the crude nutrients intakes was also performed.
During both pregnancy visits, an ultrasound examination was carried out to obtain estimates of
fetal biometry and fetal well-being and the postnatal anthropometric parameters were also
measured. Blood samples were collected at fasting, 30min, 60min and 120min of the OGTT
for the measurements of maternal glucose (GLC), insulin (INS), C-peptide (C-PEP) and
proinsulin (PI) and fasting samples for the determination of placental lactogen (HPL), insulinlike
growth factor 1 (IGF-1), insulin-like growth factor binding protein 1 (IGF-BP1), free thyroxin (FT4), cortisol (CORT) and leptin (LEPT). Infant fasting blood samples were used
for the analysis of the GLC, INS, PI, IGF-BP3 and LEPT. The plasma glucose samples were
analysed on the Beckman Glucose Analyser 2, whilst all the other analytes were measured by
an immunoassay method on 96-well plates.
Results – DESCRIPTIVE DATA.
Study participants. The majority of the study participants had completed high school
education, however were unemployed and of low and very poor socio-economic levels. In
comparison with another study from the developing world, the Pune study in India, the women
from the current study were older, heavier with greater body mass index (BMI) and they were
also taller. They had higher head and arm circumference.
Birth outcomes. The birth size of African babies in the current study, although smaller
in all parameters, was still relatively closer to the size of the Caucasian babies seen within the
Southampton (Godfrey et al. 1996) or Helsinki (Forsén et al. 1997) studies than to the birth
size of the babies from Trivandrum (Jaya et al. 1995) or Pune (Rao et al. 2001) in India.
These relatively smaller African babies have comparable (or even larger) maternal placental
sizes in relation to the mothers of both European studies. However, in comparison with the
small Indian babies, the major difference noted was a substantially smaller placental size of
the Pune mothers.
Compared to z-scores from the World Health Organization (WHO) child growth
standards (WHO Anthropo 2010), the PND study babies were born lighter and shorter with a
larger head circumference (HC). A growth delay observed near the neonatal visit was followed by catch up growth in weight for age, however no catch-up growth was observed for length for
age by the second postnatal visit.
Dietary intakes. The PND study women had pregnancy energy intakes slightly below
the national level intakes (Steyn et al. 2006), except for the energy intake at V3, which
exceeded the national level. The lower energy intake during pregnancy is attributable to a
lower intake of dietary protein and total carbohydrate. The fat intake was substantially higher
in the PND study, with levels almost double at the second postnatal visit. This discrepancy
may be due to differences between investigated populations or due to increased requirements
of energy during lactation.
In comparison with the Recommended Dietary Allowances (RDA), during the
pregnancy period women in the current study had lesser crude protein and higher carbohydrate
intake. Intake of the crude protein after delivery was low in comparison to the RDA for
lactating women. Total carbohydrate intake exceeded the RDA. The relation between the
intake of macronutrients expressed as a percentage of total energy (%E) and RDA was similar.
The current study participants had a lower intake of energy, especially during the
pregnancy period, when compared to populations in the developed world. They had a lower
intake of protein at all visits in comparison with the national average for women or with that
found in the Southampton study or when compared to the usual American diet. The energyadjusted
intake of fat and carbohydrate were comparable with the Southampton and American
data. This population in our study was therefore more comparable to that of Pune than to
American or Southampton populations. However, despite similar total energy intakes as the Pune Study, total protein and fat intakes were higher in the African mothers, which may
explain their higher weights and birthweights of their babies.
Results – ANALYTICAL DATA
Dietary intakes. Maternal dietary intakes showed significant effects on the fetal
biometrical measurements, mainly involving the fetal head, femur length and the size of
abdomen. The outcomes also show a significant relationship between maternal protein intake
and baby’s birth weight. Associations were also found for maternal dietary intakes and the
neonatal length and BMI and the markers of the infant β-cell function. Intakes of the plant
protein and polyunsaturated fat supported the linear growth. There was no correlation between
maternal dietary intake and the fetal growth rate. Effects of the total energy intake and
carbohydrate seemed to be direct, while the effect of protein and fat may be delayed, possibly
involving metabolic adaptation of the mother and the partitioning of nutrients between the
mother, placenta and fetus. (See Table: Associations between the maternal dietary intake and
the neonatal INSF1 levels, Pg. xiv).
Maternal hormones. The data of the current study show significant relationships
between maternal pregnancy hormones and fetal growth rate and the postnatal growth rate,
although maternal anthropometry and fetal gender and BMI are also significantly involved.
The maternal thyroid hormones seem to play an important role in fetal and postnatal growth
and insulin metabolism (N=76, p=0.002, ß=-0.343; AR2=0.106) in the association with the
neonatal fasting insulin. Discussion. The outcomes of the current study show that the African pregnant women
in the study had lower energy intakes attributable to a lower intake of dietary protein and total
carbohydrate.
Maternal dietary intakes showed significant effects on the fetal biometrical parameters.
Protein dietary intake was positively associated with baby’s birth weight and was shown to be
statistically significant. Associations were also found for maternal dietary intakes and the
infant postnatal BMI and the markers of the infant β-cell function. Quality of the protein and
fat has different effects on fetal/infant growth.
Maternal hormones showed correlations with fetal growth rate and the outcomes of the
current study also show that maternal hormones can affect neonatal and early postnatal infant
glucose levels and β-cell function. They are also linked to the programming of early obesity.
The maternal thyroid hormones seem to play an important role.
The maternal low energy, protein (especially plant protein) and PUFA intakes during
gestation may be the reasons for the lower z-score birth parameters of the infants in
comparison with the World Health Organization (WHO) child growth standards (WHO Anthro
2010). The disproportionally larger head of the newborn may be an outcome of the brain
sparing effect. A suggestion for an increased maternal dietary intake of energy, protein and
PUFA has been made.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/10940 |
| Date | 10 January 2012 |
| Creators | Toman, Marketa |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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