In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: In the singleton pregnancy , the mother had ulcerative colitis , and the infant , a male , had coarctation of the aorta and a ventricular septal defect .
### Output Text:
In the singleton pregnancy , the mother had ulcerative colitis , and the infant , a male , had coarctation of the aorta and a ventricular septal defect . 