The MoD is considering how the ruling will affect its policy on single parents.
A tribunal is considering how much the MoD must pay a female soldier after she won her case against the Army for sexual and racial discrimination.
Tilern DeBique, 28, was disciplined after not appearing on parade because she had to look after her daughter.
The corporal could be paid up to £100,000 for loss of earnings, injury to feelings and aggravated damages.
The MoD said personnel with children "are responsible for ensuring they have childcare arrangements in place".
Cpl DeBique was told the Army was "unsuitable for a single mother who couldn't sort out her childcare arrangements".
The judge who ruled on the MoD's appeal called it an unusual case, because Cpl DeBique was a Foreign and Commonwealth soldier serving in the British Army, as well as being a single mother.
Her daughter was initially cared for by her family in St Vincent. She then brought her child to England, and asked if a relative could come to the UK to help with childcare - but was told immigration rules did not allow it.
The corporal missed work when her child was ill, and was late for parade, resulting in disciplinary action.
Her commanding officer told Cpl Debique she was expected to be available for duty at any time.
The MoD said Cpl Debique was offered an alternative job, but left.
The tribunal criticised the Army for not helping to make childcare arrangements.
An MoD spokesman said: "The armed forces aim to achieve a working environment free from harassment, intimidation and discrimination.
"Serving personnel who are parents are responsible for ensuring they have childcare arrangements in place so that they can fulfil all of their Army duties.
"Commonwealth and Republic of Ireland citizens have access to the same levels of Army welfare support as their British counterparts."
BBC defence correspondent Caroline Wyatt said the military will be studying the case to see what they have to do better under the law with regard to single parents.
The Army will have to look very carefully at what they are asking single parents to do, she added.
The compensation hearing continues.