Her brave effort at multi-tasking has so far succeeded, and has been generally commended - apart from a bizarre attack in print from an Australian feminist who berated Jacinda for devaluing motherhood by making it appear too easy!
The other politician whose fortunes might have been compromised was Winston Peters.
Serious misgivings were expressed by his critics about his taking over the reins of government but - as befits an experienced minister - he hasn't put a foot wrong and has even distinguished himself by calling out the Australians on their immigration policies.
With the support of his fellow minister, Andrew Little, he has - not before time - held the Australian government to account for their shameful denial of human rights in their treatment of immigrants (including large numbers of Kiwis), and particularly of those below the age of majority, when they are held in detention in inappropriate conditions and denied access to legal advice, medical treatment and - in the case of school-age children - education, and are then deported without any legal process and merely by decision of the relevant minister - a minister who, this case, seems to think that young Kiwis with no convictions for any offence constitute a threat to the safety of Australians.
It cannot be said that, in standing up for the rights of Kiwis, and for the international obligations Australia has undertaken to protect human rights, Winston Peters will succeed in changing the policies of the Australian government; but he has at least made it clear that their deficiencies in this respect risk doing serious damage to Australia-New Zealand relations - with the corollary that any failure to remedy the situation would lay bare the little value the Australians apparently now place on the Anzac partnership.
While the coalition government can now feel that it has successfully negotiated what could have been a tricky period of uncertainty and lack of direction, the leader of the Opposition will have faced quite different challenges. It is a truism to say that a newly elected party leader will find his first party conference to be a difficult hurdle to clear.
He will be expected to reinforce his authority, see off any potential challengers, and satisfy his supporters that they have made the right choice. He will also want to land some telling blows on the government and persuade the wider public that he is a Prime Minister in waiting.
How did he fare? No too badly, but not as well, perhaps, as he would have liked.
He suffered an unlucky setback when he referred to his deputy as "Paula Benefit" - a slip of the tongue of the kind that could befall anyone, but that inevitably caused some amusement - but it should, perhaps, provide an object lesson in the dangers of using a private nickname for one's colleagues.
His real problem, however, remains unresolved.
He is constantly urged to make himself better known to the electorate, and he has worked hard at doing so; but the polls show that the voters have not warmed to what they know and see of him - and changing one's persona is not easily achieved.
I recall that Margaret Thatcher managed it, when she took voice lessons to change her hectoring tone to a more dulcet sound and thereby made herself more acceptable.
The risk in making such an attempt, however, is that the voters are quick to detect and punish any perceived lack of authenticity.
To sum up, then - Jacinda's parental leave has been and gone without changing the underlying political balance too much.
We have yet to see what, if any, response there might be to the emergence of little Neve Te Aroha into the public consciousness.
