Margaret Ounsted

EFFECT OF Y CHROMOSOME ON FETAL GROWTH-RATE

Abstract An earlier hypothesis, that the greater the antigenic differences between mother and conceptus the greater is the fetal growth-rate, is here extended to explain sex differences in fetal growth-rate in terms of the antigenic disparity created by the presence of a Y chromosome. This effect would be expected in the whole conceptus, and some evidence for this hypothesis can be found in the relative birth-weights of females in mixed-sex multiple pregnancies.

Head Circumference and Developmental Ability at the Age of Seven Years

ABSTRACT. Data on 365 children who had been small (SGA) average (AGA) or large (LGA) for gestational age at birth were analysed at the age of seven years. Significant positive correlations were found between head circumference and developmental scores in the SGA and LGA groups. These were mainly due to associations between relatively small heads and low scores. Familial factors, social class and sex affect both head circumference and developmental ability at this age. Their influences on these two parameters differ in degree; and in the case of sex, in direction. When account was taken of these other factors the contribution of birth‐weight group to the variance in head circumference remained high; but its contribution to developmental scores was reduced.

Maternal Constraint of Foetal Growth in Man

Two personal series of infants and their mothers were studied. Ninety infants of birth weight more than 2 S.D. below the mean were compared with 225 prospectively ascertained before the twentieth week of gestation.

Accelerated Fetal Growth

A series of 150 growth‐accelerated infants and their mothers was compared with a control series. No differences were found in social class distribution, maternal health, or the incidence of bleeding and hypertension during the proband pregnancy.

Unconstrained Foetal Growth in Man A Preliminary Note

Data are presented on the birth weights of previous liveborn young of multiparous women ascertained through a proband infant whose birth weight was more than 2 standard deviations above the mean for the duration of pregnancy.

Hand Preference: Its Provenance, Development, and Associations with Intellectual Ability at the Age of 7.5 Years

The development of 199 children was studied at regular intervals from birth to 7.5 years. On each occasion hand preference was recorded. Their preferred hand was evident in 89.4% right and 85.7% left-handers by 4 years. Analyses on 242 children seen at birth and 7.5 years showed no associations between left-handedness and nine factors representing different aspects of “birth stress.” For 12 of 15 aspects of ability at 7.5 years left-handed children had slightly higher scores than right-handers. Pathological factors do not seem to feature in the provenance or consequences of left-handedness in a normal healthy population.

Growth In the First Year of Life: Effects of Sex and Weight for Gestational Age at Birth

Fifty‐five small‐for‐dates (SFD), 56 average‐for‐dates (AFD) and 55 large‐for‐dates (LFD) babies were weighed and measured at regular intervals from birth to 12 months. Within the SFD and AFD groups weight gain was greater for boys than for girls so that by one year there were highly significant differences between the two sexes. Within the LFD group the sex difference was slight at all ages. Gain in length was similar to that for weight within each group; but head circumference showed a different pattern. Absolute increase in head circumference respectively for boys and girls between birth and one year was greatest in the SFD group and least in the LFD group. Within all three groups it was greater for boys than girls. By the age of six months AFD boys had larger heads than LFD girls and SFD boys had larger heads than AFD girls. At 12 months the head‐circumference values for LFD girls and SFD boys did not significantly differ.

FETAL GROWTH AND MENTAL ABILITY

FETAL GROWTH AND MENTAL ABILITY IN a recent annotationY2O a number of studies were cited which tended to confirm the greater than chance achievement of first-born children. Youngest children come next in achievement order, and middle children last. Data have now been published on population studies made in Birmingham and Newcastle. RECORD and his colleagueslB analysed the scores in Verbal Reasoning (VR) tests taken by 48,913 children as part of the eleven-plus examination. These were set against data recorded at the time of their birth. The results showed a striking association between VR scores and maternal age and birth order. Scores rose regularly with increasing maternal age and fell with increasing birth order. Comparison was then made of the score differences within families, where two siblings had taken the examination during the study period. The mean VR score was 1 .O lower for later born sibs than for earlier born. The difference was greater at low than at high birth ranks, and in poor rather than in well-to-do families. In Newcastlel* the IQS of 2,872 children were measured at the age of 5 years by the application of a Draw-a-Man Test. Mean IQ was highest for children born in a second pregnancy, and steadily decreased with increasing pregnancy number, falling more rapidly after the sixth pregnancy. Children born to mothers under 20 and over 40 years of age had the lowest mean IQ. It was highest for those born to mothers in their thirties. Maternal age and birth rank are linked. The mean size of family increases and mean IQ decreases with descending social class. The authors of both these studies interpret their findings in the light of the social class effect and consider that the associations are determined mainly by differences between rather than within families. The findings of a number of workers relating birthweight to intelligence have been conflicting. The variations probably reflect the different methods of investigating the subject and the different populations studied. In a study of children attending normal schools little association could be found between IQ scores and birthweight. Where groups of low birthweight infants were later examined,llI Is or groups of mentallyretarded children were studiedY8* ri definite associations have been demonstrated between low birthweight and low intelligence. In the Birmingham study,l the VR scores of 41,534 children were standardised for sex and birth rank and distributed according to birthweight. The difference on the mean between the lowest (under 2.0 kg) and the highest (4.5 kg or over) birthweight groups was 9.5 points. When data on 5,042 sib pairs were examined there was little evidence of variation in scores in relation to birthweight within the same families. However, the authors point out that birthweight variation between sibs is relatively small, and the possibility cannot be excluded that large weight differences may be associated with considerable score differences. They conclude that in a general population

BIOLOGICAL FACTORS AND FETAL GROWTH

2. (1935) ‘Forces concerned in the absorption of the cerebrospinal fluid.’ Amer. J. Physiol., 114,40. 3. Dandy, W. E. (1919) ‘Experimental hydrocephalus.’ Ann. Surg., 70, 129. 4. Davson, H. (1967) Physiology of the Cerebrospinal Fluid. London: Churchill. 5 . Bowsher, D. (1960) Cerebrospinal Fhid Dynamics in Health and Disease. Springfield, 111.: C. C. Thomas. 6. Bering, E. A. (1952) ‘Water exchange of central nervous system and cerebrospinal fluid.’ J. Neurosurg., of the methods of investigation.’J. med. Res., 31,21.