WhatToExpect.com, the exclusive home of Heidi Murkoff’s What To Expect When You’re Expecting, official launches the Pregnancy Tracker mobile app for the iPhone. The free app gives expectant moms (and dads) round-the-clock, at-their-fingertips access to America’s best-loved and bestselling pregnancy brand, What to Expect, so that they can track their baby’s amazing development – and their own fast changing and growing bodies – every day, no matter where they are.

In its beta release, the Pregnancy Tracker became an instant hit and is already the most popular pregnancy app available for the iPhone. The app has also become an attractive new marketing channel to reach prospective new parents.

What to Expect’s Pregnancy Tracker iPhone app is loaded with invaluable (and fun) interactive features that let parents-to-be follow their pregnancies week by incredible week. Moms (and dads) can calculate and count down to that momentous due date, and keep up with their baby’s astonishing rate of growth (as it works its way through the produce aisle — from raspberry-size at week eight, to plum-size at week 12, to watermelon at term).

They also get Heidi’s weekly updates on what baby’s up to development wise (week 18, twisting and rolling, week 26, opening his eyes), weekly illustrations of their growing fetus, and the opportunity to upload photos of their burgeoning bellies and turn the photos into slide shows to share with their families and friends.

WhatToExpect.com has also launched the Baby Name Finder app for the iPhone. The application includes over 15,000 baby names which can be searched by gender, alphabetically and by origin. It also contains the top baby names for each year from 1950 – 2008 and the origin and meaning of the names included. What to Expect’s Baby Name Finder application can be found along with the Pregnancy Tracker application.