Zayn Malik and Gigi Hadid’s romance has been a five-year rollercoaster of on-and-off-again - but the celebrity couple have now given birth to their first child.After confirming they were back together earlier this year, Malik has now revealed on Instagram that the couple have welcomed a "healthy and beautiful" baby girl together.Throughout their back-and-forth over the past five years, Hadid and Malik have become a popular celebrity couple.