Reading Date from Postgres Row in Laravel. Php

I m trying to create an object in Laravel, when i set the date I get an error. Thats my code:

$result = pg_query($this->conn, "SELECT * FROM cliente");
    if (!$result) {
      $this->message('Error to query cliente');
      exit;
    }
    while ($row = pg_fetch_row($result)) {
        if($row[7]== null){
            $cliente->fecha_nacimiento = null;
        }
        else{
            $fechaString = (string)$row[7];
            //$this->info($fechaString);
            $fecha = DateTime::createFromFormat('Y-m-d', trim($fechaString));
            $cliente->fecha_nacimiento =  $fecha;
        }
}

The error is:

[ErrorException]                                                             
DateTime::createFromFormat() expects parameter 2 to be string, object given

If I use Carbon:

$fecha = Carbon::createFromFormat('Y-m-d', trim($fechaString));

Getting:

[InvalidArgumentException]                  
The separation symbol could not be found  
Unexpected data found.                    
Trailing data     

Thanks in advance!

via Chebli Mohamed