Loth

Fig. 4.3 Fetal growth curves derived from longitudinal ultrasound scans of normal pregnancies, showing a normal distribution and no flattening at term.

34 weeks

Fig. 4.3 Fetal growth curves derived from longitudinal ultrasound scans of normal pregnancies, showing a normal distribution and no flattening at term.

4oÓ-

J

' 67 %

'0

1

o..%______

_J

1

^3 %

1

1

32 34 36 Weeks

38 4o 42

24 26 28

32 34 36 Weeks

38 4o 42

Fig. 4.4 'Proportionality' fetal growth curve. The line represents an equation derived from an in utero weight curve, transformed into a % term weight versus gestation curve for any predicted term (280 day) birthweight point.

% weight = 299.1 - 31.85 GA +1.094 GA2 - 0.01055 GA3.

produce individually adjusted or 'customized' norms for fetal growth in each pregnancy (Fig. 4.5).

Thus 'normal' growth is not an 'average' for the population, but one that defines the optimal growth that a fetus can achieve, that is, the 'growth potential' of each baby.

A number of studies have shown that standards for normal birthweight and growth adjusted for constitutional variation are better than local population norms to separate physiological and pathological smallness. Customized standards improve detection of pathologically small babies [14,15]. Smallness defined by customized standards were also more strongly associated with adverse pregnancy outcomes such as stillbirth, neonatal death or low Apgar scores [16] and were more closely linked with a number of pathological indicators such as abnormal antenatal Doppler, caesarean section for fetal distress, admission to the neonatal unit and prolonged hospital stay [17].

Significantly, each of these studies showed that babies that are considered small only by the (unadjusted) population method do not have an increased risk of adverse pregnancy outcome. In the general population, up to a third of babies are false positively small when general rather than individually adjusted norms for fetal growth are used, which can result in many unnecessary investigations and parental anxiety. Conversely, about a third of babies who should be suspected to be at risk are missed. In population subgroups such as minority ethnic groups, application of an unadjusted population standard results

Customized antenatal growth chart Mrs Small (1 DOB: 01/01/75)

44 42 40 38 36 34

al 32

al 32

Para 1 Pakistani Maternal height: 150 Booking weight: 49 Body mass index: 21.8

37w 0d; 2500 g; Amy

su

E

DD

I X = Fundal height O = Estimated weight by scan

-1000

Sunday..

5000

-1000

(a) Gestation week 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

11 18 25 1 8 15 22 29 6 13 20 27 3 10 17 24 1 8 15 Aug Aug Aug Sep Sep Sep Sep Sep Oct Oct Oct Oct Nov Nov Nov Nov Dec Dec Dec

44 42 40 38

30 28 26 24

(b) Gestation week Sunday.

Customized antenatal growth chart Mrs Large (1 DOB: 01/01/75)

44 42 40 38

Para 1 European Maternal height: 177 Booking weight: 78 Body mass index: 24.9

37w

1/ 0d;

250

0 g;

my

'I:

51

E

DD

I X = Fundal height O = Estimated weight by scan

3000

3000

5000

24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 11 18 25 1 8 15 22 29 6 13 20 27 3 10 17 24 1 8 15 Aug Aug Aug Sep Sep Sep Sep Sep Oct Oct Oct Oct Nov Nov Nov Nov Dec Dec Dec

Fig. 4.5 Two examples of customized fetal growth curves, using GROW.exe version 5.11 (www.gestation.net). The charts can be used to calculate previous baby weights and ultrasound estimated fetal weight(s) in the current pregnancy. Serial fundal height measurements can also be plotted. The graphs are adjusted to predict the optimal curve for each pregnancy, based on the variables entered (maternal height and weight, parity and ethnic group). In the example, a baby born at 37.0 weeks weighing 2500 g was within normal limits for Mrs Small (51st centile) but FGR for Mrs Large (5th centile) as the latter's predicted optimal growth curve is steeper. The pregnancy details entered are shown on the top left, together with the (computer-) calculated body mass index (BMI). The horizontal axis shows the day and month of each gestation week, calculated by the software on the basis of the EDD.

in even more false positives and false negatives. The individual or customized method to determine normal fetal growth is recommended by guidelines of the Royal College of Obstetricians and Gynaecologists [18].

In summary, thanks to imaging techniques such as ultrasound, normal fetal maturation and growth can be better defined. Fetal growth is subject to constitutional variation which needs to be adjusted for. Such adjustment results in better definition of normal growth, and improved identification of the fetus whose growth is pathologically affected.

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Getting Back Into Shape After The Pregnancy

Getting Back Into Shape After The Pregnancy

Once your pregnancy is over and done with, your baby is happily in your arms, and youre headed back home from the hospital, youll begin to realize that things have only just begun. Over the next few days, weeks, and months, youre going to increasingly notice that your entire life has changed in more ways than you could ever imagine.

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