Pregnant British singer Jenny Frost is in "agony" and struggling to "stand up straight" as she nears the birth of her twins.

The former Atomic Kitten star and her Spanish husband Vicente Juan Spiteri are due to become parents to two daughters next month (Feb13), but Frost is battling severe back pain due to the strain of carrying the babies.

In a post on her blog, she writes, "Backache/sciatica... To say my back has been sore this week is the understatement of the century. It's been agony. It's so bad that I can't stand up straight sometimes. Whoever said pregnancy is a beautiful thing was either a man, drunk or very lucky!"

Frost, who is already a mother to five-year-old son Caspar, from a previous relationship, also reveals she experienced additional problems over Christmas (12).

She adds, "I've had the worst acid reflux but it was especially awful on Xmas day. It was my own fault though as I had a huge dinner and then lay down. My tummy was so painful and I just kept doing really pathetic little burps that burnt like anything."