Double trouble
Twins can be identical (from one fertilised egg that splits) or non-identical (from two separate eggs). Identical twins have to be the same sex, as they have the same genes. Non-identical twins can be the same sex or one of each.
Fertility treatments make twins more likely - maybe 25 per cent of in vitro fertilisation (IVF) conceptions result in twin births. Some other treatments stimulate ovulation, which increases the chance of more than one egg being released and fertilised.
The increase in multiple births due to fertility treatments has caused concern among doctors. Some feel the practice of replacing two embryos after IVF should stop.

The effects of caffeine
Caffeine is a drug that acts as a stimulant to the heart and central nervous system, and is also known to increase blood pressure in the short term, although there is no conclusive evidence of long-term effects on blood pressure.
The effects on blood pressure are most likely when caffeine is taken in excessive quantities or by highly sensitive people. In particular, people who are hypertensive (have habitual high blood pressure), are advised to avoid caffeinated drinks, while pregnant women are advised to limit their intake of caffeinated drinks to less than 300mg per day.
Coffee has been linked with a number of the risk factors for coronary heart disease, including increased blood pressure and high blood cholesterol levels. However, no relationship has been found between coffee drinkers and the likelihood of developing coronary heart disease.

Exercises to enjoy
Activities such as brisk walking, swimming, and gentle toning and stretching classes are ideal during pregnancy.
Cycling is good exercise, too. As you get bigger, you'll find you have to get used to the changes in the distribution of your weight, and you may need to adjust your saddle and handle bars. In late pregnancy, it's safer to use an exercise bike, in case you fall.
If you were already attending an exercise class before your pregnancy, tell your instructor that you're pregnant. They'll be able to advise you on any parts of the class that are now unsuitable.
Water baby
Exercising in water is safe and enjoyable during pregnancy - and it's great for late pregnancy backache. The water supports your whole body, and you can be as energetic or relaxed as you want. Many public and private pools offer antenatal classes, often run by trained midwives or physiotherapists. Most classes begin with a sequence of gentle warm-up exercises, followed by stretches and a swim. Swimming several lengths gives you a good, safe workout.