In surah Maryam, the word for her labor pains is مخاض – makhāḍ. The root of مخاض makhāḍ is listed in most classical dictionaries as مخض m-kh-ḍ which means “to churn”. So the common theory is that labor pains are like the churning of the baby moving around. That seems reasonable. It would be on the pattern فَعال fa‘āl like سماء صباح سماع جمال etc…

But I propose the root is خوض kh-w-ḍ on the pattern مَفعال where the و is weakened. (It’s called lenition in linguistics. In the Arabic tradition, they just called it “substitution”). The root خوض means to wade through water and then metaphorically to force one’s way out. I think the imagery is clear here that the baby is forcing its way out, which is also technically more accurate as being the cause of labor pains. I’ll come back to this and the water motif later.

One problem to solve though is that we have words like the active participle ماخض meaning “in labor“. This is good evidence that the root is مخض. What I propose is they both may be correct, and I think it’s easy to see the semantic relationship between “wading” and “churning”. So how is this possible?  

One way this works is a process where a word with a prefix like   تَـ or مَـ becomes so common that it gets “stuck” due to common usage and thus forms a whole new word paradigm. This is well-attested in words like تقوى with the original root as وقي meaning to “protect” or “guard“, and the prefix ت from the pattern gets absorbed into the root! It’s a fascinating process that applies pretty much to any triliteral root beginning with a و or ي. And any word beginning with ت or ن are strong candidates for words whose original root was و, like توبة  from تاب originally آب meaning return.  Words with ت as the first root are extremely rare by the way.

This morphophonological change is called lexicalization, like in the word مكان. Initially the root is كون but due to high frequency of usage, the root gets reanalyzed as مكن. Or a word like مدينة whose original root is دين but over time a root forms into مدن. In English, a good example would be ‘percent’, which was initially ‘per centum‘, i.e. “by the hundred”

Words with م prefix are even stronger candidates of this process. If you know what you’re doing, you could literally open the Lane dictionary at م and have another screen open at أ or و and just go down the list. 

This is not intro stuff, and it probably conflicts with your understanding of how Arabic morphology works, so don’t worry if it’s hard to grasp right now. It doesn’t really help you learn the language. This is historical linguistics which you won’t find in even the most advanced Arabic classes. I wasn’t taught it when I studied Arabic. It’s just something you sort of figure out the deeper you go.

Now back to the water motif. Let’s accept the etymology of خوض and the word مخاض would be that time when the baby wades its way through the birth canal (notice the water motif in the English word canal). In the very same ayah that mentions the labor pains driving Sayyida Maryam to the tree trunk, she’s told there’s a rivulet or small stream beneath her. That word for rivulet سَريّ looks an awful lot like سُرّيّ = umbilical cord. Also remember the original meanings of نُطفة are pure water and pearl, we are created from “ejected water” in surah Tariq (i.e. her water breaking). Also, there’s the laden vessel in Surah yasin that is probably a symbol for the mother’s womb and the offspring in future generations. So in conclusion, the water<>birth motif is very strong in this passage about Maryam’s labor pains