Acta Pzdiatr Scand 66: 53-58, 1977
LOW CONCENTRATION OF PLASMA AMINO ACIDS IN NEWBORN BABIES OF DIABETIC MOTHERS M. VEJTORP, J. PEDERSEN, J . G . KLEBBE and E. LUND From Medical Department T , Bispebjerg Hospital and Diabetes Centre, Department of Obstetrics and Gynaecology YB, Rigshospitalet, Copenhagen, Denmark and the Danish Institute of Protein Chemistry, Horsholm, Denmark
ABSTRACT. Vejtorp, M., Pedersen, J., Klebe, J. G. and Lund, E. (Medical Department T, Bispebjerg Hospital and Diabetes Centre, Department of Obstetrics and Gynaecology YB, Rigshospitalet, Copenhagen, Denmark and the Danish Institute of Protein Chemistry, Horsholm, Denmark). Low concentration of plasma amino acids in newborn babies of diabetic amino acid concentrations were mothers. Acta Paediatr Scand, 66:53, 1977.-Plasma measured in maternal peripheral vein and in umbilical vein and artery at birth (caesarean section) in 6 diabetic and 5 non-diabetic pregnancies. The mean birth weight in the control group amounted to 3.9 kg as oversize of the foetus in three cases contributed to the indication for caesarean section. The infants in the diabetic group consisted of “small for gestational age” babies (mean weight 2.8 kg). Free amino acid levels in the normal group and in diabetic maternal blood were in agreement with previous investigations. No difference in amino acid concentrations in the maternal plasma was found, but the concentrations of the umbilical vein plasma were significantly lower in the diabetic group. Foetal hyperinsulinaemia may be a cause of the low amino acid concentrations. Besides, abnormalities of the placenta and maternal vascular complications increase and the mean birth weights decrease significantly through the White classes. Conditions of impairment of placental transfer of amino acids may thus be present. Characteristic features of the foetus may be consistent with the hypothesis as follows: The foetus in diabetic pregnancy is in varying degree exposed to an oversupply of glucose, hyperinsulinaemia, imbalanced uptake and a slightly diminished supply of amino acids.
KEY WORDS: Diabetes mellitus, newborn infant, amino acids
The results of the few measurements of foetal and maternal concentrations of amino acids at birth in diabetic series have been conflicting ( 3 , 4 , 8 , 18). We describe here a study of the concentrations of free amino acids in maternal peripheral venous plasma and in umbilical venous and arterial plasma at birth in a series of diabetic and non-diabetic pregnancies. A hypothesis’ as regards the size at birth of infants of diabetic mothers (IDM) is advanced.
PATIENTS AND METHODS Patients The material comprised a diabetic group of six mothers, a nondiabetic group of five mothers and their newborn infants. The diabetic series was nearly consecutive. Two pregnancies belonged to White class B and four to class D (20). The non-diabetic series was not consecutive. The pregnancies were uneventful. The urinary oestriol excretion was normal in the diabetic as well as in the control group. All of the infants were delivered by caesarean section. The indications in the diabetic series (besides diabetes) were: previous caesarean section (two), unsuccessful inActu Pzdiutr Scund 66
54
M . Vejtorp et al.
Table 1. Clinical data Mean and range
Group Diabetic (N =6) Non-diabetic (N=5)
Maternal age (years)
Gestational age (weeks)
Birth weight (kg)
Birth length (cm)
25.8 23-3 1
37.7 36-39
2.8 2.5-3.6
28.0 25-32
39.6 3 7 41
3.9 3.24.9
49.3 46-53 52.4 51-55
duction (two), breech presentation (one) and foetal tachycardia (one). In the control group the indications were: contracted pelvis and previous section (one), contracted pelvis and oversized foetus (two), breech presentation and oversized foetus (one) and placenta previa (one). In all cases the anaesthesia was performed with nitrous oxideoxygen after premedication with atropine and induction with enibomalsodium (Narcodorm) and succinylcholine. The operations were done in the morning between 8.45 and 10.00 with one exception (at 2.50 p.m. in a diabetic). At 1 min Apgar scores were 4-10 in IDM and 2-9 in the control group, at 5 min 9-10 in both groups. No neonatal deaths occurred. Table 1 summarises maternal age, gestational age, birth weight, birth length and placental weight. In the control group the mean birth weight amounted to 3.9 kg because presumed oversize of the foetus contributed to the indication for caesarean section in three cases. However, the non-diabetic mother of the baby with a birth weight of 4.9 kg had a normal glucose tolerance test in the puerperium and also in a previous pregnancy, and the mother of a baby with a birth weight of 4.4 kg was non-glucosuric, non-obese and without diabetes in the family. The amino acid ratios FIM (concentrations in umbilical venous plasmalmaternal plasma) of these two patients were in the middle of the values for the control group. Generally the birth weight of IDM is larger than that of normals (16). Consequently an IDM with a gestation time of 36-39 weeks and a birth weight of less than 2.8 kg is less than the 10 percentile and thus a "small for gestational age" baby (10). IDM constitutes a most inhomogenous population also inside one White class, and the present
Placental weight (8)
730 470-1 100 667 480- 970
series happened to comprise low-weight babies with a mean birth weight of 2.8 kg or about 0.7 kg lower than usual found in our material (16). This is of importance m comparing the foetal amino acid concentrations in the present series with those of others. The mean gestational age was shorter in IDM, but not significantly so. Besides, amino acid levels in normal pregnancies remain constant during the last trimester and into the postterm period in the mother and the foetus (23) .
Methods A few minutes before induction of anaesthesia peripheral venous blood from a maternal antecubital vein was taken in heparinized tubes. From a segment of the cord, insulated immediately after delivery, blood was withdrawn in heparinized syringes from an umbilical artery and the vein. The time interval between induction of anaesthesia and withdrawal of the samples from the umbilical cord was about 5 min. After separation by centrifugation, the proteins in 4 ml maternal plasma and 1 ml plasma from umbilical arterial and venous blood, respectively, were precipitated with picric acid, which again was removed by passage through a resin column (Dowex 2-XB). The samples were then freeze-dried and stored at -18°C. The maximal time interval between withdrawal of samples and freeze-drying was two hours. The samples were dissolved in sodium citrate buffer pH 2.2 and analyzed on Beckmann amino acid analyzers, model 120 B and 12 1 . Neutral and acidic amino acids were separated on ion-exchange resin Type M-72 (Beckman, Germany), using lithium citrate buffer as column eluant
Table 2. Torat plasma amino acids in maternal peripheral venous and umbilical venous plasma Median and range are given in mmolll plasma Maternal plasma
Foetal plasma
Ratio F/M"
Group
Median
Range
Median
Range
Median
Range
Diabetic Non-diabetic
I .68 1.60 p>O.lO
1.41-2.17 1.27-1.71
2.09 2.84 p
LOW CONCENTRATION OF PLASMA AMINO ACIDS IN NEWBORN BABIES OF DIABETIC MOTHERS M. VEJTORP, J. PEDERSEN, J . G . KLEBBE and E. LUND From Medical Department T , Bispebjerg Hospital and Diabetes Centre, Department of Obstetrics and Gynaecology YB, Rigshospitalet, Copenhagen, Denmark and the Danish Institute of Protein Chemistry, Horsholm, Denmark
ABSTRACT. Vejtorp, M., Pedersen, J., Klebe, J. G. and Lund, E. (Medical Department T, Bispebjerg Hospital and Diabetes Centre, Department of Obstetrics and Gynaecology YB, Rigshospitalet, Copenhagen, Denmark and the Danish Institute of Protein Chemistry, Horsholm, Denmark). Low concentration of plasma amino acids in newborn babies of diabetic amino acid concentrations were mothers. Acta Paediatr Scand, 66:53, 1977.-Plasma measured in maternal peripheral vein and in umbilical vein and artery at birth (caesarean section) in 6 diabetic and 5 non-diabetic pregnancies. The mean birth weight in the control group amounted to 3.9 kg as oversize of the foetus in three cases contributed to the indication for caesarean section. The infants in the diabetic group consisted of “small for gestational age” babies (mean weight 2.8 kg). Free amino acid levels in the normal group and in diabetic maternal blood were in agreement with previous investigations. No difference in amino acid concentrations in the maternal plasma was found, but the concentrations of the umbilical vein plasma were significantly lower in the diabetic group. Foetal hyperinsulinaemia may be a cause of the low amino acid concentrations. Besides, abnormalities of the placenta and maternal vascular complications increase and the mean birth weights decrease significantly through the White classes. Conditions of impairment of placental transfer of amino acids may thus be present. Characteristic features of the foetus may be consistent with the hypothesis as follows: The foetus in diabetic pregnancy is in varying degree exposed to an oversupply of glucose, hyperinsulinaemia, imbalanced uptake and a slightly diminished supply of amino acids.
KEY WORDS: Diabetes mellitus, newborn infant, amino acids
The results of the few measurements of foetal and maternal concentrations of amino acids at birth in diabetic series have been conflicting ( 3 , 4 , 8 , 18). We describe here a study of the concentrations of free amino acids in maternal peripheral venous plasma and in umbilical venous and arterial plasma at birth in a series of diabetic and non-diabetic pregnancies. A hypothesis’ as regards the size at birth of infants of diabetic mothers (IDM) is advanced.
PATIENTS AND METHODS Patients The material comprised a diabetic group of six mothers, a nondiabetic group of five mothers and their newborn infants. The diabetic series was nearly consecutive. Two pregnancies belonged to White class B and four to class D (20). The non-diabetic series was not consecutive. The pregnancies were uneventful. The urinary oestriol excretion was normal in the diabetic as well as in the control group. All of the infants were delivered by caesarean section. The indications in the diabetic series (besides diabetes) were: previous caesarean section (two), unsuccessful inActu Pzdiutr Scund 66
54
M . Vejtorp et al.
Table 1. Clinical data Mean and range
Group Diabetic (N =6) Non-diabetic (N=5)
Maternal age (years)
Gestational age (weeks)
Birth weight (kg)
Birth length (cm)
25.8 23-3 1
37.7 36-39
2.8 2.5-3.6
28.0 25-32
39.6 3 7 41
3.9 3.24.9
49.3 46-53 52.4 51-55
duction (two), breech presentation (one) and foetal tachycardia (one). In the control group the indications were: contracted pelvis and previous section (one), contracted pelvis and oversized foetus (two), breech presentation and oversized foetus (one) and placenta previa (one). In all cases the anaesthesia was performed with nitrous oxideoxygen after premedication with atropine and induction with enibomalsodium (Narcodorm) and succinylcholine. The operations were done in the morning between 8.45 and 10.00 with one exception (at 2.50 p.m. in a diabetic). At 1 min Apgar scores were 4-10 in IDM and 2-9 in the control group, at 5 min 9-10 in both groups. No neonatal deaths occurred. Table 1 summarises maternal age, gestational age, birth weight, birth length and placental weight. In the control group the mean birth weight amounted to 3.9 kg because presumed oversize of the foetus contributed to the indication for caesarean section in three cases. However, the non-diabetic mother of the baby with a birth weight of 4.9 kg had a normal glucose tolerance test in the puerperium and also in a previous pregnancy, and the mother of a baby with a birth weight of 4.4 kg was non-glucosuric, non-obese and without diabetes in the family. The amino acid ratios FIM (concentrations in umbilical venous plasmalmaternal plasma) of these two patients were in the middle of the values for the control group. Generally the birth weight of IDM is larger than that of normals (16). Consequently an IDM with a gestation time of 36-39 weeks and a birth weight of less than 2.8 kg is less than the 10 percentile and thus a "small for gestational age" baby (10). IDM constitutes a most inhomogenous population also inside one White class, and the present
Placental weight (8)
730 470-1 100 667 480- 970
series happened to comprise low-weight babies with a mean birth weight of 2.8 kg or about 0.7 kg lower than usual found in our material (16). This is of importance m comparing the foetal amino acid concentrations in the present series with those of others. The mean gestational age was shorter in IDM, but not significantly so. Besides, amino acid levels in normal pregnancies remain constant during the last trimester and into the postterm period in the mother and the foetus (23) .
Methods A few minutes before induction of anaesthesia peripheral venous blood from a maternal antecubital vein was taken in heparinized tubes. From a segment of the cord, insulated immediately after delivery, blood was withdrawn in heparinized syringes from an umbilical artery and the vein. The time interval between induction of anaesthesia and withdrawal of the samples from the umbilical cord was about 5 min. After separation by centrifugation, the proteins in 4 ml maternal plasma and 1 ml plasma from umbilical arterial and venous blood, respectively, were precipitated with picric acid, which again was removed by passage through a resin column (Dowex 2-XB). The samples were then freeze-dried and stored at -18°C. The maximal time interval between withdrawal of samples and freeze-drying was two hours. The samples were dissolved in sodium citrate buffer pH 2.2 and analyzed on Beckmann amino acid analyzers, model 120 B and 12 1 . Neutral and acidic amino acids were separated on ion-exchange resin Type M-72 (Beckman, Germany), using lithium citrate buffer as column eluant
Table 2. Torat plasma amino acids in maternal peripheral venous and umbilical venous plasma Median and range are given in mmolll plasma Maternal plasma
Foetal plasma
Ratio F/M"
Group
Median
Range
Median
Range
Median
Range
Diabetic Non-diabetic
I .68 1.60 p>O.lO
1.41-2.17 1.27-1.71
2.09 2.84 p
