Gestational age is a key piece of data used by healthcare providers to determine the timing of various screening tests and assessments of the fetus and mother throughout pregnancy. Gestational age may be assessed at any time during pregnancy, and several modes of assessment exist, each requiring different equipment or skills and with varying degrees of accuracy. Obtaining more accurate estimates of gestational age through better diagnostic approaches may initiate more prompt medical management of a pregnant patient.

1. ASSESSMENT OF
GESTATIONAL AGE
Mrs Gayathri R
First year Msc Nursing
Upasana College Of Nursing
Kollam

2. INTRODUCTION
Gestational age is a key piece of data used by healthcare
providers to determine the timing of various screening tests
and assessments of the fetus and mother throughout
pregnancy. Gestational age may be assessed at any
time during pregnancy, and several modes of assessment
exist, each requiring different equipment or skills and with
varying degrees of accuracy. Obtaining more accurate
estimates of gestational age through better diagnostic
approaches may initiate more prompt medical management
of a pregnant patient.

3. DEFINITION
Gestational age is the common term used during pregnancy
to describe how far along the pregnancy is. It is measured in
weeks, from the first day of the woman's last menstrual cycle
to the current date. A normal pregnancy can range from 38 to
42 weeks. Infants born before 37 weeks are considered
premature.

4. INDICATION
All pregnant patients should have a gestational age calculated
for safe prenatal evaluation throughout the remainder of the
pregnancy for both mother and fetus.

5. CONTRAINDICATION
• There are no specific contraindications to assessing a pregnant
patient's gestational age. However, the modality utilized to
assess gestational age may not be appropriate for certain
patients.
• Placenta previa
• Premature rupture of membranes

6. TECHNIQUES

7. Prenatal Techniques
Non-Sonographic Methods for Determining Gestational Age
Naegele’s Rule: Establish the date of the last menstrual
period by obtaining a history from the patient. From this
date, add 1 year and 7 days, then subtract 3 months. This will
approximate the estimated delivery date. The date of the last
known menstrual period will give the approximate start date
for age of the fetus.

9. Non-Sonographic…
Uterine Size: The uterus has been described as a soft and globular pelvic organ. In
pregnancy, the uterus increases in size to accommodate the developing fetus. At
approximately 12 weeks gestation the uterus becomes large enough to be
palpable just above the pubic symphysis. At 16 weeks gestation, the fundus of the
uterus can be palpated at the midpoint between the umbilicus and the pubic
symphysis. At 20 weeks gestation, the fundus can be palpable at the level of the
umbilicus. After 20 weeks of gestation, the pubic symphysis to fundal height in
centimeters should correlate with the week of gestation.

10. NORMAL UTERUS DURING PREGNANCY

11. Sonographic Methods for Determining Gestational
Age
• First Trimester Dating: Sonographic assessment within the
first 13 weeks and 6 days will provide the most accurate
estimate of gestational age. Both transvaginal and
transabdominal approaches may be used. However, the
transvaginal approach may provide a more clear and
accurate view of early embryonic structures. Although the
gestational sac and yolk sac are the first measurable markers
visible on ultrasound, these poorly correlate with gestational
age.

13.  Crown-rump
length (CRL)
The most accurate
measurement correlating with
gestational age. Using the
mean of three measurements,
CRL can be determined by
using the calipers on the
ultrasound machine, measuring
a straight line from the outer
margin of the cephalic pole to
the rump of the embryo. This
measurement can be plugged
into numerous validated tables
and formulas that correlate
well with gestational age.

14. Second Trimester Dating
If gestational age is not determined within the first trimester,
alternate sonographic techniques may be used to estimate
gestational age. These techniques are generally not
recommended as first-line options for dating but are more
helpful in determining if fetal size is within normal range.
These measurements should not change the gestational age
or delivery date if a previous CRL has been calculated within
the first trimester.

16.  Biparietal Diameter (BPD)
This biometric parameter is recommended as a strong modality for
dating because it has been extensively studied and is well
reproduced. The technique involves a transabdominal approach by
positioning the phased array or curvilinear transducer perpendicular
to the fetal parietal bones. The calvarium should appear as a
hyperechoic (bright white) structure that is smooth and symmetric.
The BPD is measured along a plane that intersects the third ventricle
and the thalami. Using the caliper function, cursors are placed on the
outer edge of the proximal skull and the inner edge of the distal skull.
This value will give the biparietal diameter.

18.  Head Circumference (HC)
This biometric parameter has been regarded as a good estimator of
gestational age with some studies suggesting superiority to the
biparietal diameter. This parameter may also be useful clinically in
assessing for growth disorders. However, to achieve the greatest
anterior-posterior diameter, the cavum septum pellucidum must be
visualized anteriorly, and the tentorial hiatus must be visualized
posteriorly. The cerebellum and lateral ventricles should not be
visualized in a standard HC view. Using the calipers, mark the cursors
on the outer margins of the calvarium bilaterally. The ultrasound
should have an elliptical measuring tool that will generate a
measurement of the perimeter of the calvarium.

20.  Femur Length (FL)
The femur can be visualized as early as 10 weeks gestation
due to its size and density on ultrasound. Using a phased
array or curvilinear transducer, align along the long axis of
the closest femur. Proximally, visualize either the femoral
head or greater trochanter and distally, visualize the
femoral condyle. Using the calipers, measure the length of
the diaphysis, at the junction of bone and cartilage, taking
care not to include the femoral head, greater trochanter, or
femoral condyle.

22.  Abdominal Circumference (AC)
The biometric parameter is more difficult to measure and is less
able to predict gestational age than the other described techniques
accurately. However, it may be useful in fetuses with cranial or limb
abnormalities and to estimate a fetal weight and note interval
growth. Using the phased array or curvilinear transducer, position
the transducer perpendicular to the fetal abdominal wall and
visualize the symmetric appearance of the lower ribs. This view
should be at the largest diameter of the fetal liver. Note, the fetal
stomach is often visualized at this level. The umbilical portion of the
left portal vein in its shortest view is another hallmark of
appropriate positioning. Using the calipers, obtain four calibration
points around the abdomen on the skin edge making sure not to
include the rib cage. The elliptical tool may also be used to calculate
circumference.

24. Third Trimester Dating
If gestational age has not been determined by the third
trimester multiple parameters are correlated with estimated
age and fetal maturity. For example, femoral epiphyseal
ossification centers are often noted at 32 weeks. Proximal
tibial ossification centers are visualized at 35 weeks. The
proximal humeral ossification centers appear in the late
trimester and have been correlated with fetal lung maturity.

26. Postnatal Techniques
Dubowitz Method: This was the historically standard method
of determining postnatal gestational age based on 34 physical
and neurologic assessments. These assessments are divided
into 6 categories: tone, tone patterns, reflexes, movements,
abnormal signs, and behaviors. Scores are assigned based on a
detailed illustration sheet. Higher scores correlate with greater
maturity. The total score can be plotted on a graph that also
correlates with gestational age.

27. New Ballard Score: This improved scoring system is used to
determine postnatal gestational age in infants as preterm as
20 weeks. The system is divided into 6 physical maturity
components and six neuromuscular components. The physical
maturity components include skin, lanugo, plantar creases,
breast, ear/eye, and genitals. The neuromuscular components
include posture, square window/wrist, arm recoil, popliteal
angle, scarf sign, and heel to ear. Detailed illustrations have
been created to assist the examiner in determining
appropriate scores which correlate with gestational age. This
exam is quicker to perform and may be more tolerable for
sicker infants.

28. COMPLICATIONS

29. Prenatal Techniques
Non-Sonographic Methods for Determining Gestational Age
• Naegele’s Rule: This rule assumes a standardized 28-day menstrual
cycle with fertilization occurring on day 14. However, many women
have irregular cycles with variability in the length of the follicular
phase affecting ovulation. History of last menstrual period may be
confounded by early pregnancy bleeding, hormonal contraceptive
use, or incorrect recall of last menstrual period date.

30. NON SONO…
• Uterine Size: This finding primarily relies on the provider’s
physical examination. This may be confounded by maternal
factors including but not limited to obesity, multiple gestation,
leiomyoma, and fibroids. The mother may also have a
retroverted uterus which will alter normal progressive
landmarks. Individual practitioner skill and experience make
findings less reliable and reproducible.

31. Sonographic Methods for Determining Gestational
Age
• Crown-rump length (CRL): This parameter becomes less accurate for
predicting gestational age and delivery date with the advancement of
gestation due to normal embryonic development and variability in
anatomic positioning. Once the CRL exceeds 84 mm, the BDP serves
as a better indicator for gestational age.
• Biparietal Diameter (BPD): This parameter becomes limited after 22
weeks gestation due to normal biologic development with variations
in fetal size and shape. If there is a physiologic or pathologic cause for
the skull size and shape to be altered, the BPD may produce false
measurements.

32. SONO…
• Head Circumference (HC): This parameter is useful for obtaining gestation age,
but multiple landmarks need to be identified before taking measurements. After
22 weeks, there is significant variation due to normal development affecting size
and shape.
• Femur Length (FC): Multiple errors may occur when obtaining this parameter
including but not limited to, non-ossified portions of the femur and not
visualizing the full femur. This can lead to incorrect gestational age calculations.
Average femur lengths may differ among certain ethnic groups or can be
indicative of pathology. Again, this parameter does have variability after 22 weeks
due to normal biologic development.

33. SONO…
• Abdominal Circumference (AC): This parameter has a wide
margin of error for determining gestational age due to
multiple factors including asymmetry of the abdomen,
changes with respiration and movement, and user skills. Like
the other parameters, significant variability is seen after 22
weeks.
• Ossification Centers: These parameters do not directly
correlate with exact gestational age. Presence of these
ossified centers are rather markers of fetal maturity which is
seen later in pregnancy.

34. Postnatal Techniques
• Dubowitz Method: Due to a large number of criteria needed
to perform the exam, this method may be more difficult to
perform on sick and preterm infants. Also, it can take up to
20 minutes to perform this exam. Studies have shown that
this method tends to overestimate the gestational age.
• New Ballard Score: Although this exam is quicker to perform,
studies have shown that this system can overestimate
gestational age in preterm infants.

35. ESTIMATION OF
GESTATIONAL AGE

36. Estimations of gestational age can be
based on:
•Menstrual periods
•Date of conception
•Fetal ultrasonography
•Physical parameters after birth (eg, using the
Ballard score)

37. BALLARD SCORE
Jeanne L. Ballard MD, author of the
New Ballard Score, is an associate
professor of Pediatrics, Obstetrics and
Gynecology at the University of
Cincinnati College of Medicine.
Dr. Ballard received her medical degree
from the Medical College of
Pennsylvania. She completed her
residency in pediatrics at Children's
Hospital Medical Center in Cincinnati
and her fellowship in neonatology at the
University of Cincinnati College of
Medicine.

38. INTRODUCTION
The Ballard Maturational Assessment, Ballard Score, or Ballard Scale is
a commonly used technique of gestational age assessment. It assigns a
score to various criteria, the sum of all of which is then extrapolated to the
gestational age of the fetus. These criteria are divided into physical and
neurological criteria. This scoring allows for the estimation of age in the
range of 26 weeks-44 weeks. The New Ballard Score is an extension of the
above to include extremely pre-term babies i.e. up to 20 weeks.
It was developed in 1979.

39. NEUROMUSCULAR MATURITY

40. PHYSICAL MATURITY

42. ASSESSMENT OF NEUROMUSCULAR MATURITY

43. POSTURE

44. SQUARE WINDOW

45. ARM RECOIL

46. POPLITEAL
ANGLE

47. SCARF SIGN

48. HEEL TO EAR

49. ASSESSMENT OF PHYSICAL MATURITY
SKIN LANUGO

50. PLANTAR SURFACE
BREAST

51. LOW SET EAR
EYE
NORMAL EAR

52. GENITALS
MALE & FEMALE
AMBIGOUS GENITALS

53. Based on gestational age,
each neonate is classified as:
• Premature: < 34 wk gestation
• Late pre-term: 34 to < 37 wk
• Early term: 37 0/7 wk through 38 6/7 wk
• Full term: 39 0/7 wk through 40 6/7 wk
• Late term: 41 0/7 wk through 41 6/7 wk
• Postterm: 42 0/7 wk and beyond
• Postmature: > 42 wk

54. SCORE
Each of the above criteria are scored from 0 through 5, in the
original Ballard Score. The scores were then ranged from 5 to
50, with the corresponding gestational ages being 26 weeks
and 44 weeks. An increase in the score by 5 increases the age
by 2 weeks. The New Ballard Score allows scores of -1 for the
criteria, hence making negative scores possible. The possible
scores then range from -10 to 50, the gestational range
extending up to 20 weeks. (A simple formula to come directly
to the age from the Ballard Score is Age=((2*score)+120)) / 5

56. LARGE FOR GESTATIONAL AGE
Large for gestational age (LGA) is an indication of
high prenatal growth rate.
LGA is often defined as a weight, length, or head
circumference that lies above the 90th percentile for
that gestational age.
Macrosomia, which literally means "long body", is
sometimes used for LGA. Some experts consider a
baby to be big when it weighs more than 8 pounds
13 ounces (4,000 g) at birth, and others say a baby is
big if it weighs more than 9 pounds 15 ounces
(4,500 g). A baby is also called “large for gestational
age” if its weight is greater than the 90th percentile at
birth

57. SYMPTOMS
 Large fundal height
During prenatal visits, your health
care provider might measure your
fundal height — the distance from
the top of your uterus to your pubic
bone. A fundal height that measures
larger than expected could be a sign
of fetal macrosomia.

58.  Polyhydramnios
Too much amniotic fluid — the fluid
that surrounds and protects a baby
during pregnancy — might be a sign
that your baby is larger than
average.The amount of amniotic fluid
reflects your baby's urine output, and
a larger baby produces more urine.
Some conditions that increase a
baby's size might also increase his or
her urine output

59. CAUSES
• Genetic factors
• Maternal obesity
• Maternal diabetes

60. RISK FACTORS
• Maternal diabetes
• Maternal obesity
• Excessive weight gain during pregnancy
• Previous pregnancies
• Having a boy
• Overdue pregnancy
• Maternal age

61. COMPLICATIONS
Maternal risks
•Labor problems
•Genital tract lacerations
•Bleeding after delivery
•Uterine rupture

62. Newborn and childhood risks
•Lower than normal blood sugar level
•Childhood obesity
•Metabolic syndrome

63. PREVENTION
• Schedule a preconception appointment
• Monitor your weight
• Manage diabetes
• Include physical activity in your daily routine

64. SMALL FOR GESTATIONAL AGE
Small for gestational age (SGA)
newborns are those who are smaller
size than normal for the gestational
age, most commonly defined as a
weight below the 10th percentile for
the gestational age.

65. CAUSES
Maternal factors:
•High blood pressure
•Chronic kidney disease
•Advanced diabetes
•Heart or respiratory disease
•Malnutrition, anemia
•Infection
•Substance use (alcohol, drugs)
•Cigarette smoking

66. Factors involving the uterus and placenta:
• Decreased blood flow in the uterus and placenta
• Placental abruption (placenta detaches from the uterus)
• Placenta previa (placenta attaches low in the uterus)
• Infection in the tissues around the fetus

67. Factors related to the developing baby (fetus):
• Multiple gestation (for example, twins or triplets)
• Infection
• Birth defects
• Chromosomal abnormality

68. PROBLEMS
• Decreased oxygen levels
• Low Apgar scores (an assessment that helps identify babies
with difficulty adapting after delivery)
• Meconium aspiration (inhalation of the first stools passed in
utero) which can lead to difficulty breathing
• Hypoglycemia (low blood sugar)
• Difficulty maintaining normal body temperature
• Polycythemia (too many red blood cells)

69. MANAGEMENT
 Ultrasound
 Doppler flow
 Mother's weight gain
 Gestational assessment

70. PREVENTION OF SGA
Prenatal care is important in all pregnancies, and
especially to identify problems with fetal growth. Stopping
smoking and use of substances such as drugs and
alcohol are essential to a healthy pregnancy and can
reduce the risk for sudden infant death syndrome (SIDS)
and other sleep-related infant deaths. Eating a healthy
diet in pregnancy may also help.

71. APGAR SCORE
• The Apgar score is a method to
quickly summarize the health
of newborn children against infant
mortality.
• VirginiaApgar an anesthesiologist at
New York- Presbyterian hospital,
developed the score in 1952 to
quantify the effects of obstetrics
anesthesia on babies.

72. FIVE CRITERIA OF APGAR SCORE
Score of 0 Score of 1 Score of 2
Component
Skin color blue or pale all over
blue at extremities,
body pink
(acrocyanosis)
no cyanosis
body and extremities pink
Appearance
Pulse rate absent < 100 beats per minute > 100 beats per minute Pulse
Reflex irritability grimace no response to stimulation grimace on suction or aggressive stimulation cry on stimulation Grimace
Activity none some flexion
flexed arms and legs that resist
extension
Activity
Respiratory effort absent weak, irregular, gasping strong, robust cry Respiration

73. MIND MAP SHOWING SUMMARY OF APGAR SCORE

74. INTERPRETATION OF APGAR SCORE
• The test is generally done at 1 and 5 minutes after birth and may be
repeated later if the score is and remains low.
• Scores 7 and above are generally normal
• 4 to 6, fairly low
• 3 and below are generally regarded as critically low and cause for
immediate resuscitative efforts.
• A low score on the one-minute test may show that the neonate
requires medical attention.
• An Apgar score that remains below 3 at later times, such as 10, 15, or
30 minutes, may indicate longer-term neurological damage, including
a small but significant increase in the risk of cerebral palsy.
• A score of 10 is uncommon, due to the prevalence of transient
cyanosis, and does not substantially differ from a score of 9.

75. ASSESSMENT BY ULTRASONOGRAM
The advent of ultrasound has allowed a more direct
means of assessing fetal structures and development.
Measurements of a wide variety of parameters have
been devised to establish gestational age. Ultrasound
assessment of gestational age is feasible in a majority
of pregnancies and may be used to establish
gestational age with greater accuracy than physical
examination.

76. First-Trimester Assessment
GESTATIONAL SAC MEAN DIAMETER.
• It is identified by transabdominal ultrasound as early as 5
weeks' gestation and may be seen as early as 4 weeks'
gestation by transvaginal ultrasound.
• The gestational sac is an echo-free space containing the fluid,
embryo, and extraembryonic structures.
• The sac is measured inside the hyperechoic rim, including
only the echo-free space.
• The gestational sac is imaged first in the longitudinal plane,
obtaining long axis and anteroposterior measurements
perpendicular to each other.

77. • Then, in the transverse plane at the level of the
anteroposterior measurement, the width measurement is
obtained.
• The three measurements are averaged to obtain the
gestational sac mean diameter.
• The accuracy of gestational sac measurement as a predictor
of gestational age has been evaluated in only one report and
was found to be approximately ±1 week.

79. CROWN-RUMP LENGTH.
• The crown-rump length (CRL) is a measurement of the
embryo, usually identified at 6 to 7 weeks' gestation.
• The embryo is measured along its longest axis to obtain the
CRL measurement.
• Crown-rump length may be used to accurately date
pregnancy between 7 and 13 weeks' gestation.
• The technique involves measurement of the fetal length
from the tip of the cephalic pole to the tip of the caudal
pole.

80. • The fetus should be at rest and assuming its natural
curvature.
• At 5 to 6 weeks' gestation, distinct landmarks cannot always
be identified but heart motion usually can be detected
centrally.
• As the pregnancy continues, the head can be easily identified
from the rest of the body.
• After 12 weeks' gestation excessive curvature of the fetus
may lead to erroneous shortening of CRL measurement;
therefore, other measurements, such as the biparietal
diameter, should be used to estimate gestational age.

81. Ultrasound image of a fetus at 10 weeks' gestation. The crown-
rump length is measured along the longest axis of the fetus
( between the arrows)

82. Second- and Third-Trimester Assessment
BIPARIETAL DIAMETER.
• The biparietal diameter (BPD) is one of the most commonly
measured parameters in the fetus.
• Campbell was the first investigator to link fetal BPD to
gestational age.The BPD may be rapidly and reproducibly
measured by ultrasound examination from 12 weeks'
gestation until the end of pregnancy.

83. • The BPD is imaged in the transaxial plane of the fetal head at
a level depicting thalami in the midline, equidistant from the
temporoparietal bones and usually the cavum septum
pellucidum anteriorly.
• Although several methods have been used to measure BPD,
the most commonly accepted method is measurement from
leading edge to leading edge (outer-to-inner).

84. Ultrasound image with biparietal diameter measurement ( between the
solid arrows, outer edge to inner edge) and fronto-occipital diameter
measurement ( between the open arrows ).

85. HEAD CIRCUMFERENCE.
• The head circumference (HC) measurement may be used to
estimate gestational age in a similar manner to BPD
measurement. Although tracing of the outer perimeter of
the head (by trackball on the ultrasonic equipment or by
digitizer) is the most reliable means of measuring HC.
• The accuracy of gestational age estimation by HC
measurement is comparable with that of BPD measurement.
However, in fetuses with abnormal head shape, either
brachycephaly or dolicocephaly, HC may be a more accurate
predictor of fetal age than BPD.

86. ABDOMINAL CIRCUMFERENCE.
Measurement of the fetal abdominal circumference (AC) is
obtained in the transaxial view of the fetal abdomen. The AC is
measured at the level of the fetal liver, using the umbilical
portion of the left portal vein as a landmark. The fetal
stomach is at the same level, which is slightly caudad to the
fetal heart and cephalad to the kidneys. The AC measurement
is taken from the outermost aspects of the fetal soft tissues.
Measurement of the AC is performed in the same manner as
that of the HC.

87. Ultrasound image with anteroposterior ( solid arrows)
and transverse ( open arrows) diameter measurements.

88. FEMUR LENGTH.
The femur is the largest of the long bones, least moveable,
and easiest to image. The femur may be adequately visualized
from 14 weeks' gestation until delivery. It is measured along
the long axis of the bone; a straight measurement of the
osseous portion is taken from one end to the other,
disregarding bone curvature. The femoral neck and both
proximal and distal epiphyseal cartilages are excluded from
the measurement.

89. Linear array image of the fetal femur. The femur length is
measured between the arrows.

90. Ultrasound Predictors of Gestational Age
Estimated Range for
Parameter* 95% of Cases
Gestational sac mean diameter ± week
Crown-rump length ± 5–7 days
BPD, 12–26 weeks ± 10–11 days
HC, 12–26 weeks ± 10–14 days
AC, 12–26 weeks ± 10–14 days
FL, 12–26 weeks ± 10–20 days
BPD, 27–42 weeks ± 2–3 weeks
HC, 27–42 weeks ± 2–3 weeks
AC, 27–42 weeks ± 2–3 weeks
FL, 27–42 weeks ± 2–3 weeks

91. • When menstrual dates fall within the confidence
limits of the ultrasound assessment, the role of
ultrasound is to confirm menstrual dates.
• When menstrual dates fall outside the confidence
limits of ultrasound assessment, assignment of dates
should be based on ultrasound assessment of
gestational age.
• When menstrual dates are unknown, assignment of
dates should be based on ultrasound assessment of
gestational age.

92. Growth-Adjusted Sonographic Age
• Gestational age estimation using a single biparietal diameter
is accurate within a margin of ±10 to 11 days in the second
trimester. Gestational age can be more accurately predicted
by obtaining paired BPD measurements (the first from 20 to
26 weeks' gestation and the second from 31 to 33 weeks'
gestation) and assigning gestational age by a method
developed by Sabbagha and co-workers known as growth-
adjusted sonographic age (GASA).

93. CONCLUSION
Gestational age is a measure of the age of a pregnancy which
is taken from the woman's last menstrual period (LMP), or the
corresponding age of the gestation as estimated by a more
accurate method if available. Such methods include adding 14
days to a known duration since fertilization (as is possible in in
vitro fertilization), or by obstetric ultrasonography.

94. BIBLIOGRAPHY
• Nima Bhaskar, Text book of midwifery and obstetrics, EMMESS medical
publishers, 1st edition.
• D.C Dutta, Text book of obstetrics and gynecology, New central agency, 6th
edition.
• Wongs;Merilyn,Essentials of Pediatric Nursing,8th edition,Elsievier Publication.
• Rimple Sharma, Essentials of Pediatric Nursing,2th edition,Jaypee Brothers
Medical Publishers.
• Manoj Yadav,A Text Book Of ChildhealthNursing,2011 edition,Choice books &
printers (P) ltd.
• https://www.stanfordchildrens.org/en/topic/default?id=small-for-gestational-
age-90-P02411
• http://www.glowm.com/section_view/heading/Assessment+of+Gestational+Age
+by+Ultrasound/item/206

95. THANKYO
U…