Women who drink whilst trying to conceive could be stunting the growth of their placenta, new research suggests.
And the effect continues after conception, meaning that damage can be done before they know they are pregnant.
Scientists at the University of Queensland found that the restricted placental growth meant that fewer nutrients reached the embryo, potentially damaging the foetus.
The children of women who drink during pregnancy are known to be small, leaving them liable to type 2 diabetes, high blood pressure and obesity later in life.
But little research has been done into the effects from conception to actual knowledge of pregnancy, when many women stop drinking.
Although the experiments used rats, the researchers believe the results point towards further study that might help women.
Dr Jacinta Kalisch-Smith said: “We found early alcohol exposure reduced blood vessel formation in the placenta, and this led to fewer nutrients being delivered to the embryo.
“Early exposure to alcohol, between four days before and four days after fertilisation, restricted the growth and function of the placenta in rats.
“We wanted to know whether early alcohol exposure could affect the development of the early embryo and the placenta.
“Using a rat model, we assessed the ability of the embryo to implant into the uterus, and, later, how well blood vessels formed in the placenta.”
The research, published in the journal Development, showed the placentas of female embryos were particularly susceptible, with up to a 17% reduction in size and a 32% drop in blood vessel formation, limiting its ability to transport nutrients.
Dr Kalisch-Smith added: “This has implications for human health by helping to explain, in part, why babies exposed to alcohol in the womb are often born small.
“It is important to understand the causes of low birth weight, because it has been shown to be an independent risk factor for diseases later in adulthood, such as type 2 diabetes, hypertension and obesity.”
She continued: “The next part of this project is to see whether nutrient supplementation can reduce or even prevent the adverse effects of alcohol exposure.”