A News Letter Devoted To Practical Pediatric Practice

BD Gupta

Ass Editor :

RK Maheshwari

Mohan Makwana

Anil Arora

Regional Editors

Pankaj  Agrawal

Avinash  Bansal

Anil  Jain

PC  Khatri

Priyanshu  Mathur

Jai Singh  Meena

Adarsh  Purohit

Editorial advisory Board

Neeraj Gupta

Manoj Jangid

Rakesh Jora

Amarjeet Mehta

Lakhan Poswal

GS Sengar

Pramod Sharma

Anurag Singh

Kuldeep Singh

S Sitaraman

Head circumference

Head circumference is a

measurement of a child’s head around its largest area. It measures the distance from above the eyebrows and ears and around the back of the head. The brain volume, a child achieves by age of 1 year, helps to determine  intelligence later in life.

Head circumference is measured to find if there is a potential problem or if something needs to be watched, e.g. if head grows fast, it could indicate hydrocephalus.

Head growth during infancy remained a significant predictor of IQ, with a full- scale IQ increasing an average of 1.56 points for each 1-SD increase in growth.

Head circumference (HC) during antenatal period

Head circumference is one of the basic biometric parameters used to assess fetal size. HC together with biparietal diameter (BPD), abdominal circumference (AC), and femur length (FL), are computed to produce an estimate of fetal weight. In the second trimester, this may be extrapolated to an estimate of gestational age and an estimated due date (EDD)

Head circumference enlarges by approximately 1 mm per day between 26  and 32  weeks, and about 0.7 mm per day between 32 and 40 weeks of gestation.

Mean head circumference

26 weeks                 242 mm

30 weeks                  281 mm

32 weeks                 297 mm

36 weeks                  325 mm

38 weeks                  335 mm

40 weeks                  345

Head circumference in postnatal period

Prematures

The average rate of head growth in a healthy premature infant is 0.5 cm in the 1st 2 wk, 0.75 cm in the 3rd wk, and 1.0 cm in the 4th wk and every week thereafter until the 40th wk of development.

Term infants

Normal head circumferences in term infants range from 32 to 38 cm (.Mean 35 cm)

Head circumference growth velocity:

At birth: 35 cm. increases by 2 cm per month,

At 3 months: 41 cm then increases by 1 cm per month,

At 6 month: 44 cm and then increases by 0.5 cm per month,

At 12 months: 47 cm which then increases by 2 cm in second year,

At 2 years: 49 cm and thereafter it increases by1 cm per year,

At 3 years: 52 cm

Adults: 56-58 years

Microcephaly is defined as a head circumference 3 standard deviations (SDs) below the mean for age and sex or roughly less than the 2nd percentile. Microcephaly is frequently associated with intellectual disability and neurological abnormalities:

1.     Craniosynostosis.

2.     Chromosomal abnormalities.

3.     Hypoxic ischemic encephalopathy.

4.     Antepartum infections.

5.     Antenatal exposure to drugs, alcohol or certain toxic chemicals.

6.     Hereditary, familial and genetic disorders.

7.     Severe malnutrition.

Macrocephaly refers to an overly large head. The circumference of a person’s head is more than two standard deviations above average for their age. Or their head is larger than the 98th percentile.

Various important causes:

1.    Familial.

2.    Neurocutaneous disorder (e.g., neurofibromatosis).

3.    Chromosomal defect (e.g., Kleinfelter syndrome).

4.    Storage disorder.

5.    Hydrocephalus.

6.    Chronic subdural hemorrhages.