Chances of having twins rise with age

Thirty five-year-old Gladys Bulinya from Nzoia, Western Kenya has 12 children, all of them twins born between 1993 and last year. This is the highest set of twins reported but there could be many others in the country given that doctors confirm that there is a high growth in the rate of twins due to the wider availability of infertility treatment. However, parents rarely undergo the treatment hoping to have twins or multiple births; their aim is usually to have one healthy baby- more than one at the same time is a bonus.

Reseacrh

Research confirms that:

• Twins tend to run in families, and so a woman who is herself a twin or has a twin relative is more likely to give birth to twins than a woman who has no twins in her family.

• Women who conceive after the age of 40 are four times more likely to give birth to twins than those who conceive at the age of 20.

• It is quite usual for the birth of twins to follow the birth of a single child.

• Most twins are born prematurely (the average gestation period is 37 weeks) and are underweight.

• There is a high incidence of cot deaths in twins.

• Twins tend to be slower to acquire speech, and are more likely than other children to have speech problems that require specialist help.

Twins are either identical or non-identical. When identical twins are conceived, a single egg that is already fertilised separates into two identical parts. Each part develops into a baby. Since each child comes from the one egg, these twins (monozygotic) are always of the same sex and possess the same inherited characteristics.

When non-identical twins are conceived, two entirely separate eggs are fertilised by separate sperm at the same time. Since each child comes from different eggs, these twins (dizygotic) are no more alike than any other brother and sister.

Birth order

Yet according to studies even identical twins are not exactly the same in every way. While it is true that they have a greater similarity of heartbeat and pulse rate than non-identical twins, clear differences often emerge in other areas. For instance, parents frequently find that one identical twin is right-handed while the other is left-handed.

The left-handed child is likely to be the smaller twin. Twins often have different handwriting styles, and there are likely to be personality differences. It is normal for twins to pass developmental milestones at slightly different times.

The birth order of the twins (which one actually emerged first) has no effect on their psychological development.

Twins present certain practical difficulties in the early years, especially with their basic management such as who to give attention to first and who to feed first. Once a basic routine has been established, parents then have to cope with life outside the home. Parents have to choose whether to place twins in the same class in nursery or school, or to separate them.

Separation can make starting at nursery difficult, since each child will have to cope without the support of her twin; but this may be offset by the advantage that each can establish her own identity. At some point, twins have to develop separate lives, and the later parents leave it, the harder it becomes for the children.

Parents often report that each child positively thrives when given the chance to be in a class of her own, away from her twin, because each is treated individually.