id	keyword
american_scientific_journal-1214	levels
american_scientific_journal-1214	pregnancy
american_scientific_journal-1214	pregnant
american_scientific_journal-1214	trimester
american_scientific_journal-1214	urea
american_scientific_journal-1214	difference
american_scientific_journal-1214	creatinine
american_scientific_journal-1214	control
american_scientific_journal-1214	group
american_scientific_journal-1214	1st