Hi J.,
Every baby is different, especially when it comes to developmental and medical concerns. It's great to hear that other women have experienced the same thing that you are concerned about, but that does not necessarily mean that their experiences will adequately apply to you. In general, if you have a concern of this nature, press your doctor for more information. If you're not satisfied, besides asking other moms (there is definitely value in this), look for info on the the internet from reputable sources such as WebMD, Medscape, Mayo Clinic, and sites that carry the HONcode label (honesting and legitimacy in medical reporting).
BTW, if you trust your pediatrician, who has had primary experience with hundreds or even thousands of babies, then I would not be concerned if he or she is not concerned (although that does not mean that you shouldn't trust your gut instincts -- there's great value in that, too). I'm sure the doctor will reevaluate at your next well baby check, if it appears necessary. If you DON'T trust your pediatrician, then it's probably time to start hunting for a new doctor!
The article below was written by an expert from the Mayo clinic. The last paragraph should be fairly comforting.
(article begins here)
Microcephaly: When your baby's head is abnormally small
What causes microcephaly in an infant?
- Agnes / North Carolina
Mayo Clinic pediatrician Jay Hoecker, M.D., and colleagues answer select questions from readers.
Answer
Microcephaly is a rare neurological disorder in which the circumference of an infant's head is significantly smaller than average for children of the same age and sex. Microcephaly may be present at birth (congenital) or develop later in infancy.
Microcephaly usually occurs when the brain fails to grow at a normal rate. As a result, the child's skull doesn't enlarge to its normal size. This disorder is often associated with mental retardation.
Causes of microcephaly may include:
Fetal alcohol syndrome
Decreased oxygen to the fetal brain (cerebral anoxia) due to pregnancy complications or complications during delivery
Craniosynostosis — the premature fusing of the joints (sutures) between the bony plates that form an infant's skull
Chromosomal abnormalities
Infections of the fetus during pregnancy, such as toxoplasmosis, cytomegalovirus, German measles (rubella) or chickenpox (varicella)
In most cases, there's no specific treatment for microcephaly. Treatment is usually directed at managing the signs and symptoms associated with the disorder. If microcephaly due to craniosynostosis is detected early, treatment may include surgical opening of the sutures to let the brain grow normally.
If you're concerned about the size of your child's head, talk to your doctor. Doctors use growth rate charts — similar to those for height and weight — to compare your child's head circumference with that of other children of the same age and sex.
It's important to note that heads with circumferences in the 3rd, 2nd and even 1st percentiles are just small heads. Microcephaly is a head circumference that is significantly below the 1st percentile.
(end article)
If you want more detailed information, the following article written by a MedScape expert pediatric nurse will give you more complete information than you've received so far.
BTW, forget the allergy angle -- allergies don't cause every problem in the universe. In fact, trying to pin an allergic source to this issue doesn't make physiological sense, especially since your baby is growing overall, which indicates that he is being well nourished and is not having problems absorbing nutrients. It just goes to show you that not everyone who posts on this site knows what they're talking about! :-)
BTW, you can find this posting at http://www.medscape.com/viewarticle/463561
Article starts here:
How Should I Evaluate Small Head Size in Infants With Small Parents?
Question
How do I determine if head growth/circumference is appropriate when small size may be in the family history? I have patients that begin to drop below the 5th percentile, but I suspect this may not be a problem because of the size of their petite parents. Is there a formula based on the circumference of parents' heads?
Asked by Shatzie Montellano, MSN, FNP-C
Response from Laurie Scudder, MS, RN-C, PNP
Adjunct Assistant Professor, School of Health Sciences, George Washington University, Washington, DC, and Pediatric Nurse Practitioner in a primary care pediatric practice, Columbia, Md.
A child with growth that is trending downward on the growth curve is always a concern. Head circumference should never be measured and assessed in isolation but rather as part of the child's repeated growth measurements that include height and weight and an evaluation of parental and sibling stature. A child whose growth is decreasing, and crossing major centiles, should indicate that an investigation for growth failure is needed. (A report titled "Evaluating Pediatric Growth and Nutrition: Guidelines for the Primary Care Clinician," may provide guidance. In addition, the Centers for Disease Control (CDC) released new growth charts in 2000, which are available for download from their Web site.
It is important that growth be measured accurately and plotted at every well-child visit. The new growth charts, unlike the 1977 National Center for Growth Statistics (NCHS) charts used in the past, are based on a national sample of children of all major ethnic groups and include both bottle- and breast-fed infants. "The differences between the 1977 NCHS Growth Charts and the 2000 CDC Growth Charts are most pronounced in the head circumference-for-age charts. In general, the 2000 percentiles for head circumference are higher than the 1977 percentiles until age 4-6 months. At this point, a crossover occurs, and the 2000 curve becomes lower than the 1977 curve."[1] Microcephaly is rarely associated with overall growth failure.[2]
You describe a situation in which head growth is falling below the 5th percentile. However, your question does not note that this decline is accompanied by a corresponding decrease in height and weight. Microcephaly is defined as a head circumference that measures more than 3 standard deviations below the mean for age and sex.[3] It may also be suspected in full-term newborns and infants under the age of 6 months whose head circumference is smaller than that of their chest.[4]
Microcephaly is divided into primary and secondary categories. Primary microcephaly is usually evident at birth and associated with a brain insult that occurred early in fetal life. It is typically accompanied by severe mental retardation. It is often associated with skull deformities, such as backward sloping of the forehead and narrowing at the temples and fontanelles that close earlier than expected.
Secondary microcephaly occurs from an insult to the brain later in fetal life or in the perinatal period.[5] Brain injury after 2 years is not likely to be associated with severe microcephaly. Some causes of secondary microcephaly, such as Rett syndrome, may not be noted until 2-4 months of age when head growth begins to decelerate and are accompanied initially by a slowing in acquisition of developmental milestones and later a loss of milestones.[6]
It can be helpful to measure the head circumference of other family members and plot the measurements on an age-appropriate chart. For older children, the Nellhaus curves for the ages 0 to 18 years are widely used. These were developed by merging data from 14 studies of head growth published worldwide between 1948 and 1965.[7] They do have limitations, however, because the majority of those included in these studies were white Americans. A 1997 study conducted in Turkey on 408 adults computed male and female adult head circumference charts plotted against weight and height.
More important, though, is your overall assessment of the child. Is the small head size part of growth that is trending downward, or does the child have a small head and is staying at the same percentile with relation to a standardized growth curve chart? Serial head circumference measurements are more important than a single determination, particularly when the variation is small.
There are 2 major concerns that should be addressed when a child presents with microcephaly. The first is developmental delay and mental retardation, since microcephaly may be the presenting condition in a wide range of neurodevelopmental disorders. A child with a small head warrants ongoing, serial, developmental assessments to be sure that he or she is meeting age-appropriate developmental milestones. Thorough exams should be conducted at well-child visits to document that the child is developmentally appropriate, does not have unusual facies or other features, has open fontanelles at an age where they should be open, and appears to have normal vision and hearing.
The second concern is craniosynostosis, resulting from premature closure of the cranial sutures, as the cause of the suspected microcephaly. This may occur if many or all sutures close prematurely. Typically, however, craniosynostosis is not associated with microcephaly because the inhibited growth along the involved suture is compensated for by increased growth at open sutures and fontanelles.[5] Closure of only 1 suture will not cause impaired brain growth. The management of craniosynostosis is directed toward preserving skull shape.
The bottom line with this child is that an isolated measurement should be followed by repeated careful assessment of both growth and development. Yes, small parents may lead to small children, but before that conclusion is made, other causes must be ruled out.
Posted 11/11/2003
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References
Measuring and plotting head circumference. Department of Health and Human Services: Available at: http://depts.washington.edu/growth/ofc/text/page1a.htm Accessed on October 18, 2003.
Barness LA, Cooper DS. Handbook of Pediatric Physical Diagnosis. 7th ed. Philadelphia: Lippincott Williams & Wilkins; 2001.
Behrman RE, Kligman RM, Jensen HB. Nelson's Textbook of Pediatrics. 16th ed. Philadelphia: WB Saunders; 2000.
Moe PG, Seay AR. Neurologic and muscular disorders. In: Hay WH, Haywood AR, Levin MJ, Sondheimon JM, eds. Current Pediatric Diagnosis and Treatment. 16th ed. New York: Lange Medical Books/McGraw-Hill; 2003.
McMillan JA, DeAngelis CD, Feigin RD, Warshaw JB. Oski's Pediatrics: Principles and Practices. 3rd ed. Philadelphia: JB Lippincott; 1999.
Rich J. Degenerative central nervous system (CNS) disease. Pediatr Rev. 2001;22:175-176.
Johnson DE. Does size matter, or is bigger better? The use of head circumference in preadoption medical evaluations and its predictive value for cognitive outcome in institutionalized children. Available at: http://www.russianadoption.org/Headcircumferencedj.htm Accessed October 18, 2003.
BTW, Your question piqued my interest because I am currently working on an presentation to educate laboratory personnel and general practioners on different aspects of infectious diseases that can be passed from a mother, often unsuspecting, to a developing baby. Many of these diseases cause microcephaly, which is a condition marked by an abnormally small head size, developmental delay and mental retardation. I do NOT suspect this for your baby, so DON'T FREAK OUT! It's just an explanation of why your question interested me. I'm assuming that you had a normal pregnancy and carry either natural immunity to or vaccinated against viruses such as rubella, parvovirus, Epstein-Barr and CMV, and practice good hygiene around cats so that you did not contract primary toxoplasmosis, as is the usual and fortunate case in this country.