Small for gestational age fetal growth restriction low birth weight

2. Small for gestational agefetal growth restrictionlow birth weight 29/11/92 Mojgan Barati

3. Definition For the purposes of this guideline, SGA birth is defined as an estimated fetal weight (EFW) or abdominal circumference (AC) less than the 10th centile and severe SGA as an EFW or AC less than the 3rd centile

4. IUGR • Growth restriction implies a pathological restriction of the genetic growth potential. • As a result, growth restricted fetuses may manifest evidence of fetal compromise (abnormal Doppler studies, reduced liquor volume)

5. LBW • Low birth weight (LBW) refers to an infant with a birth weight < 2500 g.

6. customized • Historically SGA birth has been defined using population centiles. But, the use of centiles customisedfor maternal characteristics (maternal height, weight, parity and ethnic group) as well as gestational age at delivery and infant sex, identifies small babies at higher risk of morbidity and mortality than those identified by population centiles • Several studies have shown that neonates defined as SGA by population–based birthweight centiles but not customised centiles are not at increased risk of perinatal morbidity or mortality.

7. FGR/SGA • Fetal growth restriction (FGR) is not synonymous with SGA. • Some, but not all, growth restricted fetuses/infants are SGA while 50–70% of SGA fetuses are constitutionally small, with fetal growth appropriate for maternal size and ethnicity. • The likelihood of FGR is higher in severe SGA infants

8. For thepurposes of this guideline • SGA birth is defined as an estimated fetal weight (EFW) or abdominal circumference (AC) less than the 10th centile and severe SGA as an EFW or AC less than the 3rd centile. • Other definitions will be discussed where relevant.

9. divided Small fetuses are divided into • normal (constitutionally) small, • non–placenta mediated growth restriction, for example; - structural - chromosomal anomaly, - inborn errors of metabolism - fetal infection, • Placenta mediated growth restriction

10. Placental • Maternal factors can affect placental transfer of nutrients, for example; - low pre–pregnancy weight, - under nutrition, - substance abuse - severe anaemia. • Medical conditions can affect placental implantation and vasculature and hence transfer, for example; - preeclampsia, - autoimmune disease, - thrombophilias, - renal disease, - diabetes and - essential hypertension

11. As a group, structurally normal SGA fetuses are at increased risk of perinatal mortality and morbidity but most adverse outcomes are concentrated in the growth restricted group

12. Clinical examination • Clinical examination is a method of screening for fetal size, but is unreliable in detecting SGA fetuses.

13. Diagnosis of a SGA • Diagnosis of a SGA fetus usually relies on ultrasound measurement fetal abdominal circumference or estimation of fetal weight

14. Management of the SGA • Management of the SGA fetus is directed at timely delivery

15. surveillance tests A number of surveillance tests are available, including • cardiotocography, • Doppler and • ultrasound to assess biophysical activity but there is controversy about which test or combination of tests should be used to time delivery, especially in the very preterm fetus (< 30+0 weeks of gestation).

16. summary • 1- Determination of true gestational age of fetus based on accurate LMP or CRL in first trimester • 2- EFW centile and AC centile • 3- <10 centile follow by maternal monitoring for hypertension and fetal surveillance tests • 4- rare cases of aga are FGR