Britney Spears is pregnant, the 40-year-old pop star announced on Instagram Monday.

Spears wrote in her post that shortly after a trip to Maui with her fiancé, Sam Asghari, she started to gain weight.

She wrote, "So I got a pregnancy test ... and uhhhhh well ... I am having a baby."

The news of the pop star's pregnancy comes months after a judge ended her 13-year conservatorship

after a highly publicized legal battle with Spears' father. This arrangement meant

Spears had very limited control over her life and the decisions she could make — including on her career, finances and health.

The singer was placed under her conservatorship in 2008 after suffering from mental health issues.

In a bombshell testimony last June, she told a Los Angeles Superior Court judge that she wanted to have another baby,

but she was forced to keep an IUD in place, in accordance with her conservatorship.

Spears is already a mom to two boys: Sean Preston Federline, 16, and Jayden James Federline, 15,

Britney Spears pregnant