According to Facebook's amended S1 registration with the Securities and Exchange Commission (SEC) on Monday, the popular social network reported its first quarter-over-quarter plunge in advertising revenue in at least two years; with the company's $1.06 billion revenue for the 2012 first quarter marking a 6 percent drop from its 2011 fourth-quarter revenue figures.

While Facebook said that it possibly was the seasonal advertising trends which led to the company's somewhat surprising first-quarter revenue decline, it is being assumed that the drop is seemingly an indication that the astounding growth of the social network may be slowing down as it prepares to go public in the biggest ever Internet initial public offering (IPO), expected in mid-May.

With the Facebook IPO reportedly looming large, the company's Monday filing with the SEC comprised a number of notable new financial and performance numbers, including the revelation that it now has over 901 million monthly active users, as compared to 845 million in the previous quarter.

Going by the Facebook filing, the last one year period, from March 2011 to March 2012, has witnessed a 33 percent increase in the social network's total membership, with the figures for monthly average users being 680 million a year back.

As per Facebook, the mentioned one-year period also witnessed a 41 percent increase - from 372 million to 526 million - in number of daily average users; while the number of people using Facebook on mobile devices recently surpassed the 500 million monthly average user mark!