For most men, the thought of taking on the burden of pregnancy from their partners would seem like a nightmare, but it’s all part and parcel of seahorse life. After mating, female seahorses and pipefish lay their eggs into a special pouch in the male’s belly and he carries the developing babies to term. They may seem like a shoe-in for a Dad-of-the-year award but this apparent display of paternal perfection has several macabre twists.
A recent study showed that pregnant pipefishes can also become vampiric cannibals, absorbing some of their brood for nutrition if their own food supplies are running low. Now, Kimberley Paczolt and Adam Jones from Texas A&M University have found that male pipefishes are also selective abortionists. They’ll kill off some of the youngsters in their pouches if they’ve mated with an unattractive female, or if they’ve already raised a large group of young in an earlier pregnancy.
The pouch isn’t just an incubator for the next generation. It’s a battleground where male and female pipefish fight a war of the sexes, and where foetal pipefish pay for this conflict with their lives.
Pregnant women are generally advised to avoid drinking alcohol and for good reason – exposing an unborn baby to alcohol can lead to a range of physical and mental problems from hyperactivity and learning problems to stunted growth, abnormal development of the head, and mental retardation.
But alcohol also has much subtler effects on a foetus. Some scientists have suggested that people who get their first taste of alcohol through their mother’s placenta are more likely to develop a taste for it in later life. This sleeper effect is a long-lasting one – exposure to alcohol in the womb has been linked to a higher risk of alcohol abuse at the much later age of 21. In this way, mums could be inadvertently passing down a liking for booze to their children as a pre-birthday present.
Now, Steven Youngentob from SUNY Upstate Medical University and Jon Glendinning from Columbia University have found out why this happens. By looking at boozing rats, they have found that those first foetal sips of alcohol make the demon drink both taste and smell better.
The duo raised several pregnant rats on diets of either chow, liquids or liquids that had been spiked with alcohol. The third group eventually had a blood alcohol concentration of about 0.15%, a level that would cause a typical human to slur, stagger or become moody.
When the females eventually gave birth, month-old pups born to boozy mothers were more likely to lick an alcohol-coated feeding tube than those whose mothers were tee-total. These rats had been born with more of a taste for booze.
Our health isn’t just affected by the things we do after we’re born – the conditions we face inside our mother’s womb can have a lasting impact on our wellbeing, much later in life. This message comes from a growing number of studies that compare a mother’s behaviour during pregnancy to the subsequent health of her child.
But all of these studies have a problem. Mothers also pass on half of their genes to their children, and it’s very difficult to say which aspects of the child’s health are affected by conditions in the womb, and which are influenced by mum’s genetic legacy.
Take the case of smoking. Doing it while pregnant is bad news for the foetus, and studies have suggested that children whose mothers smoke during pregnancy are more likely to be born prematurely, be born lighter, have poorer lung function, and be more likely to die suddenly before their first birthday. More controversially, they may even show higher levels of behavioural problems including autistic disorders and antisocial tendencies.
Biologically, these results make sense, but many of these risks can be inherited too. For example, genetic factors can strongly influence both a person’s susceptibility to nicotine addiction and their propensity for violent behaviour. A mother’s genes could also affect the birth weight of her child.
To untangle these influences, the ideal experiment would involve randomly implanting foetuses either in the wombs of their own mothers, or those of unrelated women. That’s possible in animals but deliberately doing so in humans would be both unethical and impractical. Nonetheless, Frances Rice from Cardiff University realised that this experiment was actually well underway.
Since the advent of in vitro fertilisation (IVF) technology in the late 1970s, many mothers have nourished babies in their womb, who weren’t genetically related to them. Here was an ideal chance to study the effects of conditions in the womb, without any confusion caused by shared genes.