The study of almost 3,800 pregnancies was carried out on the border of Thailand and Myanmar (Burma) as part of the Wellcome Trust-Mahidol University-Oxford University programme in tropical medicine.
Low birth weight can have severe health consequences. It is a major cause of death and ill health in infancy and can have a long-term impact on health in adult life.
Previous studies have suggested that malaria during pregnancy reduces birth weight whether or not the mother is showing any symptoms. However, these studies have been hampered by difficulties in dating pregnancies accurately and in diagnosing malaria infection early on in pregnancy.
The researchers based at the Shoklo Malaria Research Unit (SMRU) on the border of Thailand and Myanmar used ultrasound scans to provide the first direct evidence of the effect of malaria on foetal growth in pregnancy. Their findings are published in the journal PLoS One.
Antenatal ultrasound, which is essential for dating pregnancy accurately, is becoming more widely available in developing countries. Ultrasound also allows the diameter of the foetus’ head to be measured, which the researchers believe is the most appropriate indicator of growth restriction for infections that occur in early pregnancy.
The researchers found that the diameter of the average foetus’ head was smaller when malaria infection occurred in the first half of pregnancy when compared to pregnancies unaffected by malaria.
We need to make sure that pregnant woman are educated about the risks of malaria in pregnancy.
Dr Marcus Rijken
On average at the mid-pregnancy ultrasound scan, the foetuses’ heads were 2% smaller when affected by malaria. Even a single infection of malaria that had been treated was associated with reduced foetal head diameter, irrespective of whether the woman had shown symptoms or not.
However, early treatment of malaria with effective drugs may allow for growth to recover later in pregnancy. While a single early-detected and well-treated malaria episode had an effect on foetal head size half-way through pregnancy, this was not seen when the baby was born.
Dr Marcus Rijken of SMRU, who is first author on the study, said: ‘By using antenatal ultrasound screening, we have provided clear evidence that malaria infection affects the growth of a child in the womb, even when the infection is caught early and treated. This can increase the risk of miscarriage and affect the child’s health in later life.
‘Strategies to prevent malaria in pregnancy have focused on the second half of pregnancy, when most of the foetal weight gain takes place, but our works suggests that we need to broaden our efforts to focus on the first trimester, too.
‘We need to make sure that pregnant woman are educated about the risks of malaria in pregnancy and where possible in areas of high risk, offer preventative medication from early pregnancy onwards.’
Source: Wellcome Trust