Fetal Development and Growth

Fetal Development and Growth

Major congenital anomalies are those which may severely affect the life of the individual or require major surgery for correction. In the absence of

intensified preconception care of diabetes, the incidence of major congenital

Table 4. Examples of insulin dosage regimens Problem

Solution

Isolated fasting BG ?100 mg/dl 12–20 U NPH at bedtime Increased FBG+prebreakfast ?130 mg/dl

12–20 U NPH at bedtime FBGs nl, PPBGs ?130 mg/dl

6 U Reg, 20 U N 30 min prebreakfast All FBGs and PPBGs elevated

60 kg at 0.7 U/kg>42 U/day 10 U Reg, 18 U N prebreakfast (2/3)

7 U Reg, 7 U N predinner (1/3) (double dosage for obesity) or Reg before each meal, N hs

Predinner BG low, prelunch BG high 14 N prebreakfast, 4U Reg predinner BG =60 at 3 a.m., FBG ?100 mg/dl

Move NPH to bedtime Problems c timing of injections and meals,

Use Lispro (H) or Aspart or high BG 1 h premeals, low BG 3–4 h postmeals

Humalog Ó at half the dose of Reg, 5 min premeal

Strong dawn phenomenon (increased insulin 2–6 U Reg at 4 a.m. by algorithm requirement at 4–8 a.m.)

SC insulin pump c increased basal rate Variable day-to-day response to insulin injections

Do not inject near exercising muscle in arm or leg Be sure CHO intake is consistent Adjust premeal Reg by premeal BG

anomalies in infants of diabetic mothers (IDM) is 6–12%, compared to 2% in infants of a control population or in infants of diabetic mothers with HbA 1c near normal at the beginning of pregnancy. This means that primary care physicians treating diabetic women of reproductive age must evaluate them for the possibility of becoming pregnant and inform them of the risks of unplanned pregnancies related to the level of hyperglycemia. Intensified pre- conception care of diabetes has been shown to reduce the frequency of major congenital anomalies to that of a the nondiabetic population in a cost-effective manner.

Ultrasonography in early pregnancy confirms the dating of gestation and may detect neural tube defects that occur with a higher than normal incidence with maternal BGs ?10 mmol/l (180 mg/dl). Later in pregnancy at 18–22 weeks, targeted perinatal sonography and fetal echocardiography can detect congenital heart defects or other severe anomalies. Subsequent examinations at 28 and 37 weeks measure fetal growth and well-being. En- Ultrasonography in early pregnancy confirms the dating of gestation and may detect neural tube defects that occur with a higher than normal incidence with maternal BGs ?10 mmol/l (180 mg/dl). Later in pregnancy at 18–22 weeks, targeted perinatal sonography and fetal echocardiography can detect congenital heart defects or other severe anomalies. Subsequent examinations at 28 and 37 weeks measure fetal growth and well-being. En-

Prevention of maternal hyperglycemia and excess weight gain with dietary and insulin treatment throughout pregnancy produce near normal levels of branch chain amino acids, FFAs, and triglycerides, and reduce the frequency of fetal macrosomia. The glycemic threshold for fetal macrosomia seems to

be postprandial peak values above 7.2 mmol/l (130 mg/dl). On the other hand, average peak postprandial BG levels below 6.1 mmol/l (110 mg/dl) may be associated with insufficient fetal growth and small-for-dates infants, who may also have complications in the neonatal period.

Another reason for more serious intrauterine growth restriction is maternal vascular disease, especially diabetic nephropathy with hypertension and reduced glomerular filtration. The poor fetal growth is apparently related to inadequate uteroplacental perfusion. All fetal parameters may be below normal on ultra- sonographic measurements (but head sparing is common), and oligohydram- nios is frequent. With diabetic nephropathy the goals of maternal treatment are control of hyperglycemia and hypertension (=135/85), adequate rest, and limitation of protein intake to 60–80 g/day. Antihypertensive agents which are safe and effective in pregnancy include methyldopa, diltiazem (reduces proteinuria in diabetic patients more than other calcium channel blockers), clonidine, and prazosin. These medications may need to be added in sequence. Use of b-blockers, such as labetolol, should be limited in mid-pregnancy due to a possible association with fetal growth restriction, and angiotensin- converting enzyme inhibitors should never be used in pregnancy due to poten- tial damage to the fetal kidneys.