For the past six months or so, Pinterest was definitely the hottest thing on the web with phenomenal growth rates every month which eventually lead the social networking site to the top 30 US sites. But now it seems that Pinterest’s growth rate may have settled down as demonstrating a “humanly-accepted” growing numbers in March.

According to new comScore numbers published by CNBC’s Julia Boorstin, while on February Pinterest reached for nearly 18 million unique visitors and a 52% increase compared to January, on March Pinterest surpassed slightly the 20 million unique visitors mark which indicates on a 12% monthly rise in visitors.

Even though we certainly can’t call the February-March 12% monthly visitors increase “slow”, it is still much slower than the 52% jump on January-February, the 56% boost it had on December-January and the 55% rise on November-December. Just to be sure that Pinterest growth has indeed decelerated, I made few more inquiries.

Although I don’t completely trust the accuracy of Alexa stats, I still believe they can show trends pretty well. And so, I have examined Pinterest’s Alexa reach stats (not traffic rank!) in order to verify if there is some decline in the site’s trending numbers.

You can see from the data above that in the last 30 days throughout March (until April 3rd) the site’s reach have rose by 16.7% (which is pretty similar to comScore’s data) while in the last three months it grown by more than 280%. Meaning that Alexa stats are confirming also that the social networking site’s growth is slowing down.

Reasons For Pinterest Drastic Decline In Growth

Pinterest has encountered a couple of difficulties recently:

• Users Unhappy About the Profile Redesign– After the site decided to change the user profiles design on mid-March, it received mostly (very) negative feedback from its community.
• Spam Attack– On late March it has been revealed that many spammers are using auto-bots to create spam accounts in order to generate affiliate commissions revenue.

Even though the easy thing to do is to attribute the decline in growth to any of those events, at this point in time I don’t think it is related to any of these cases. I think that the slowing down derives from the natural course of all things. What I mean is that it was only natural for the site to demonstrate a decline in the growth rates.

After such a fast rise which obviously included many new user registrations, it is pretty safe to assume that most of the site’s visitors are now relatively new (three-four months or so)- In December 2011 Pinterest had less than 8 million unique visitors while in March, as stated, it crossed the 20 million unique visitors mark.

All those many fresh users MUST understand how this whole social pinboard thing works while experiencing with it a bit before recommending it to their friends, which essentially drives all social networking sites growth.

Julia Boorstin mentions in her story that Twitter was “stuck” on the 20 million unique visitors for a while (about 3-4 months from what I’ve checked) before continuing to climb furthermore (currently Twitter has more than 140 million active users a month).

So for all you Pinterest fanatics out there, I don’t think there’s any reason to be concerned!