[Study of the causes of fetal growth restriction with unclear etiologies]

To investigate different factors related to fetal growth restriction (FGR) and to find out the possible causes of FGR with unclear etiologies.

Sixty-three women who were suspected of FGR during pregnancy between March 2002 and March 2003 were included in this study. Their age, body mass index (BMI) before pregnancy, and gestational weeks were recorded at the time when they were first diagnosed. Haemoglobin levels, haematocrit (HCT), TORCH, anticardiolipin antibody (ACA), 50 gram glucose challenge test (50g GCT), 75 gram oral glucose tolerance test (75g OGTT), leptin levels, systolic/diastolic (S/D) ratio by color doppler monitor and chlamydia trachomatis (CT) were detected and urine culture was done in these groups during the same period. The gestational week, birth weight, body length and the gender were recorded at the delivery period. The FGR group was then divided into two subgroups according to the birth weights: study A group whose birth weights were lower than 10th% of the birth weights at the given gestational weeks (29 cases) and study B group whose birth weights were beyond 10th% (34 cases). The chromosome, leptin, C-peptide, insulin and TORCH of umbilical blood were measured at delivery. The other 25 normal pregnant women were included as control and the same tests were performed accordingly.

The fasting glucose and the third hour's glucose of 75 gram oral glucose tolerance test of study A were (3.8 +/- 0.6) mmol/L and (4.5 +/- 1.1) mmol/L. The fetal leptin, C-peptide, and insulin were (7.3 +/- 5.2) ng/ml, (0.5 +/- 0.3) nmol/L and (2.3 +/- 1.3) mU/L. The S/D ratio of umbilical artery, maternal and fetal infection rate of CMV, positive rate of ACA-IgM and the rate of asymptomatic bacteriuria were 3.06, 20.7%, 24.1%, 44.8% and 62.1% respectively. The fasting glucose and the third hour's glucose of 75 gram oral glucose tolerance test of study B were (4.4 +/- 0.7) mmol/L and (4.6 +/- 1.1) mmol/L. The fetal leptin, C-peptide, and insulin were (13.2 +/- 11.3) ng/ml, (0.7 +/- 0.4) nmol/L and (4.3 +/- 3.3) mU/L. The S/D ratio of umbilical artery, maternal and fetal infection rate of CMV, positive rate of ACA-IgM and the rate of asymptomatic bacteriuria were 2.63, 2.9%, 0%, 5.9% and 44.1% respectively. The fasting glucose and the third hour's glucose of 75 gram oral glucose tolerance test in control were (4.3 +/- 0.7) mmol/L and (5.3 +/- 1.2) mmol/L. The fetal leptin, C-peptide, and insulin were (20.5 +/- 12.0) ng/ml, (1.0 +/- 0.4) nmol/L and (6.3 +/- 4.0) mU/L. The S/D ratio of umbilical artery, maternal and fetal infection rate of CMV, positive rate of ACA-IgM and the rate of the asymptomatic bacteriuria were 2.80, 0, 0, 0 and 24.0% respectively. All these items were significantly higher in study A than those in the control (P < 0.05). There was no significant difference between the study B and the control in all the items.

Many factors may play a role in the pathogenesis of FGR, including the maternal blood glucose level, the ability for fetus to use the glucose, the infection of some microorganisms, insufficiency of the blood supply and the autoimmunity of the mother. Finding out the possible causes of FGR and managing them accordingly may improve the outcomes of the fetus.