A comparison of the early growth of twins and singletons
1School of Medicine, Division of Paediatrics and Child Health, University of Leeds, UK. the.greens@talk21.com
Insights
Twin growth differs from singletons. While twins have shorter birth lengths, their later height growth is comparable, but head circumference remains smaller. Singleton growth charts are not suitable for twins.
Area of Science:
- Pediatric Growth Studies
- Twin and Singleton Development
- Human Gestation and Postnatal Growth
Background:
- Twin birth weight is typically lower than singletons, with less known about birth length and postnatal growth.
- The impact of shorter gestation in twins on their early development is often overlooked.
Purpose of the Study:
- To compare the growth trajectories of healthy twins and singletons during the first four years of life.
- To establish growth references for twins considering gestational age.
Main Methods:
- Utilized birth length data from English twins (1990-1997) to create reference values for gestational ages 33-40 weeks.
- Tracked weight, length/height, and head circumference up to age 4 using questionnaires.
- Included follow-up data for preterm twins to assess extrauterine growth.
Main Results:
- Twins exhibited reduced birth length compared to singletons at similar gestational ages, more pronounced in boys.
- Postnatal weight gain was faster in singletons, but twin length/height showed no deficit.
- Twin head circumferences were consistently smaller than singletons throughout the study period.
Conclusions:
- Normal twin early growth patterns significantly diverge from those of singletons.
- Singleton growth references are inappropriate for accurately assessing twin development.
Background:
It is well known that the birth weight of twins is less than that of singletons, but there is less information about how birth lengths compare and how twins grow in the postnatal and early childhood period. The implications of the shorter duration of gestation of twins in comparing their postnatal progress with that of singletons are seldom taken into consideration.
Aims:
The study aimed to compare the growth of healthy twins and singletons over the first 4 years of life.
Subjects And Methods:
Birth length data on English twins born between 1990 and 1997 were used to produce reference values for gestational ages from 33 to 40 weeks. Follow-up data of weights and lengths up to the equivalent of 40 weeks' gestation are reported on some of these infants who were born pre-term. On the basis of questionnaires, the growth of twins in terms of weight, length/height and head circumference has been followed up to 4 years of age.
Results:
Mean birth length of twins showed a fall-off when compared with singletons at comparable gestational ages, which was more marked in boys than girls and evident earlier. Extrauterine growth of twins born pre-term was comparable to that of adequately nourished twins remaining in utero until term. Much of the smallness of twins at birth was because of their shorter gestation. Subsequently singletons gained weight faster. Lengths/heights showed no deficit compared with singletons. Head circumferences of twins were, however, smaller than singletons throughout.
Conclusions:
The early growth of normal twins differs markedly from that of singletons. It is important to recognize that singleton reference values do not correctly reflect the growth of twins.
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