Question: when is the first us done in pregnancy
[{'answer': "5 weeks ' gestational age", 'provenance': [{'wikipedia_id': '576327', 'title': 'Obstetric ultrasonography', 'start_paragraph_id': 18, 'start_character': 69, 'end_paragraph_id': 18, 'end_character': 95, 'bleu_score': 1.0, 'section': 'Section::::Medical uses.:Early pregnancy.\n'}]}, {'provenance': [{'wikipedia_id': '576327', 'title': 'Obstetric ultrasonography', 'start_paragraph_id': 18, 'start_character': 0, 'end_paragraph_id': 18, 'end_character': 599, 'bleu_score': 0.9147192115400311, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15045375771524334219}, 'section': 'Section::::Medical uses.:Early pregnancy.\n'}]}]