bertie this is a VERY quick search, and this is way out of my subject area so i have no means of assessing its quality, but i have found the following (not sure how much of this is freely available - i get access through work):
The social construction of gender and its influence on suicide: a review of the literature, Journal of Men's Health, 2008. they say:
"Marital and parental status
A relatively robust finding in the suicide literature is the greater risk of suicide among the widowed, separated and divorced, and those living alone, compared with married adults [68] and [76]. However, there are important differences between women and men in this association, with higher risks experienced by non-married men compared with non-married women [55] and [68]. Divorce is a significant risk factor for suicide for men, but not women [54], [77] and [78]. Widowhood is also a greater risk factor for suicide for men, especially among the young and the very old [68] and [79].
Why might marital status be more protective for men compared with women? It is worth noting that marriage is known to reduce risk behaviours such as heavy drinking [80], and a range of factors associated with socially constructed gender roles play a part in the way marriage protects men from harm. Constructions of gender mean that marriage, which offers emotional and social integration, is particularly important for men who have fewer alternative close relationships [38] and [78]. Men are more vulnerable to suicide following the break-up of a marriage or death of a spouse because they are less likely to be socially connected, while negative emotions such as pessimism, anxiety, uncertainty and sadness following a personal setback such as a relationship break-up have a more marked effect [38]. In the United States and other developed Western countries, divorce may be particularly devastating for men because they are mainly the ones who lose their home, children and family, leading to feelings of resentfulness and anger while reducing their self-esteem [78].
Being a parent also has an association with suicide risk but again this association is gendered. A number of studies have reported that having a young child protects women against suicide, but that the effect is less marked for men [2], [3] and [81]. This may be because family roles within hegemonic masculinity focus on economic success and the status of a good breadwinner rather than caring responsibilities. For women social constructions of femininity include family roles and a caring orientation and this may offer women benefits when they fulfil such stereotypes. Conversely, rates of suicide among women may increase if childlessness is viewed as a transgression of perceived gender roles or if pregnancy outside marriage is stigmatised [2]."
so they are speculating whether having children is associated with more positive feelings and that is suicide preventive, rather than that a mother might feel the responsibility of making sure they are cared for after suicide of the parent, which would prevent them committing suicide
that article also notes that in china (at that time) women had higher suicide rates than men. i wonder why that might be?