FILE PHOTO - New Zealand Prime Minister Jacinda Ardern smiles as she answers a question during a media conference in Sydney, Australia, November 5, 2017. REUTERS/David Gray/File photo

(Reuters) - The approval rating for New Zealand’s pregnant prime minister, Jacinda Ardern, has soared and support for her Labour Party has surged to its highest in 15 years, according to a poll released on Monday, nearly four months after her coalition government was sworn in.

The 1 NEWS Colmar Brunton political survey showed support for Labour had jumped to 48 percent, rising nine percentage from a December poll. It was Labour’s best showing since 2003 and gave it a clear lead over the opposition National Party which slipped three points to 43 percent.

Labour’s center-left coalition, which brought an end to almost 10 years of National’s center right rule, plans to pour money into social services and housing and strike a more protectionist stance by tightening up foreign investment rules.

Ardern’s popularity swept to 41 percent, giving her a massive 21 percentage point lead over opposition leader Bill English who will resign from parliament at the end of February.

The poll was conducted between February 10 and 14 so it did not fully capture English’s resignation announcement.

Ardern, 37, is expecting her first child in June. She is the first New Zealand prime minister to hold office while pregnant.

While Labour’s popularity rose in the polls its junior coalition partners fared less well. The survey showed support for the progressive Green Party slipped to 5 percent, and backing for New Zealand First fell to three percent.

The poll also showed an increase in the number of people who expected the economy to get better.