Early menopause can increase the risk of a potentially lethal brain condition, research has shown.
The younger a woman is when she undergoes "the change" the more likely she is to suffer a cerebral aneurysm, scientists discovered.
Aneurysms are abnormal bulges in arteries that can burst, causing sudden loss of blood.
A cerebral aneurysm is often only discovered when it ruptures, resulting in a potentially fatal or disabling brain haemorrhage.
Although rare, the condition is extremely serious. Half of those who suffer a burst artery in the brain are likely to die, and one in five is severely disabled.
US scientists found that both later menopause and use of hormone replacement therapy (HRT) protected against cerebral aneurysm.
Each successive four year increase in the age at which a woman went through the menopause lessened the risk by around 21%, while HRT reduced the risk by 77%.
The pattern may be linked to levels of the female sex hormone oestrogen, researchers believe.
After the menopause oestrogen levels drop sharply, while they are raised by HRT. Women are also generally more prone to cerebral aneurysms than men.
The findings appear in the latest online issue of the Journal of NeuroInterventional Surgery.
Researchers looked at medical and reproductive data on 76 women who had survived a cerebral aneurysm after the menopause.
Their information was compared with that from more than 4,500 participants in a large US women's health study.
Of the aneurysm survivors, one in four (26%) had experienced a young menopause before the age of 40 compared with one in five of the comparison group.
The study authors, led by Dr Michael Chen, from Rush University Medical Centre in Chicago, wrote: "There is a trend showing that an earlier age at menopause is associated with the presence of a cerebral aneurysm. This suggests that loss of oestrogen earlier in a woman's life may contribute to the pathogenesis (development) of cerebral aneurysm.
"These data may identify a risk factor for cerebral aneurysm pathogenesis and also a potential target for future therapies."