Research reveals women in politics are often "damned if they do, and damned if they don't" in ways that men are not. Those who are mothers have their competence questioned - can they simultaneously do their job and raise a child? And not just do both, but do both equally well? (Although who knows what measures are used).
The traditional separation between private and public spheres continues to feed stereotypes about women's political leadership. Yet when women in politics don't have children, they face other kinds of questions and criticisms.
Julia Gillard, Australia's first female Prime Minister, was vilified by one of her opposition colleagues for being "barren", by others for being partnered but unwed, while some suggested her choice to be childless showed she lacked empathy.
A potential Canadian Premier, Danielle Smith, had her sincerity on family issues challenged because she did not have children. In response, Smith released a statement about her struggles with fertility. We seldom if ever see men needing to justify publicly their decision or capacity to become fathers.
An analysis in 2002 found Helen Clark's childlessness was a constant reference point for the media up until that point in her political career; over the same period she was also portrayed as lacking emotion, and having a lack of femininity.
By contrast, when Jenny Shipley became prime minister, motherhood and traditional family life featured, portraying her political persona as maternal and thus fundamentally unthreatening.
Women political leaders are often stuck between a rock and a hard place. Evidence suggests that to be successful politicians women must perform politics like their male counterparts, by minimising or removing family obligations, or the anticipation of future family obligations.
Studies show women politicians are more likely to be single and childless than they are to be mothers, while male politicians are most often family men.
Some women have been successful in becoming political leaders and mothers, but many delay their political ambitions until their children are grown. In New Zealand, between 1984 and 2008, 19 per cent of women in ministerial positions had entered Parliament by the age of 34 (only one of these had children), the majority were over 40.
By contrast, 37 per cent of men who became Cabinet ministers had entered Parliament by the age of 34, the majority of whom were fathers.
More generally, women holding political office while pregnant is not new. As Esme Hall recently noted, we can think of Ruth Richardson, Whetu Tirikatene-Sullivan, Katherine Rich and Nanaia Mahuta. Green MP Holly Walker had her first daughter in 2013 before leaving office in 2014 election and currently two Labour MPs, Willow-Jean Prime and Kiri Allan have babies. Ardern's Government has been the first to formally allow babies into the debating chamber.
Nevertheless, it remains the case that the parliamentary timetable is not family friendly, child care facilities are often limited and taking parental leave and breastfeeding are not yet normalised. Studies from the UK indicate mothers in politics undertake "military-styled planning" to manage and often mention "maternal guilt".
It shouldn't have to be like this. Diversity in leadership is desirable in both politics and business. Motherhood, actual or anticipated, should not preclude election to political office and political leadership should not require our political representatives being unencumbered by caring responsibilities.
Instead, our political institutions and the norms and values embedded within them need transforming so that those who have parenting and other care roles are welcomed and celebrated rather than criticised for their self-sufficiency.
Jacinda Ardern is leading this potential transformation. In becoming a mother while Prime Minister, she is rejecting, explicitly and symbolically, the view that women are less serious or committed to political work if they have family obligations.
Implicitly, it will put more pressure on employers, public and private, to facilitate flexibility, and financially support, the participation of women and men in parenting and paid work.
Finally, the role model effect cannot be underestimated. Research tells us the more women enter politics, stand for elite positions, and push back against traditional understandings about how to combine the roles of mother and politician, the more likely future generations of women will participate in politics.
This is an important next step in shaking up the inherently gendered world of politics and potentially normalising pregnancy in politics. The world will be watching, not just Ardern but us, the New Zealand public, to see how accepting we are of motherhood in politics.
Here's hoping we do okay, if for no other reason because its 2018.
* Professor Jennifer Curtin is director of the Public Policy Institute at the University of Auckland.
